Enteropnuesta

@techreport{bullock1940the1,
    author = "Bullock, T. H",
    title = "The functional organization of the nervous system of Enteropnuesta",
    year = "1940",
    howpublished = "Biological Bulletin, Marine Biological Laboratory, Woods Hole, Mass., v. 79, p. 91-113",
    note = "talkorigins\_source = {true}; raw\_reference = {Bullock, T. H., 1940, The functional organization of the nervous system of Enteropnuesta: Biological Bulletin, Marine Biological Laboratory, Woods Hole, Mass., v. 79, p. 91-113.}"
}

Larvae of Saccoglossus horsti were reared in the laboratory, and their developmental history from the egg to the five gill-slit stage studied. The immature eggs varied from 0.23 to 0.30 mm in length and from 0.15 to 0.22 mm in breadth. They were irregular, opaque, finely granular and creamish grey in colour. They became spherical on maturing. Fertilization resulted in the rapid erection of a fertilization membrane, making the eggs buoyant. Two similar polar bodies were extruded shortly afterwards, marking the plane of the first cleavage which, with the second, was holoblastic and meridional. Subsequent cleavages were different in the animal and vegetative tiers. There was evidence of radial cleavage during the 16- to 32-cell stage. A hollow blastula was formed at the 9th to 10th cleavage stage, and gastrulation by invagination followed. The blastocoele was completely obliterated and a typical archigastrula resulted. This rapidly became uniformly ciliated and developed a telotroch around the closing blastopore. The component cilia of the telotroch imparted a slow rotatory movement to the embryo. Axial elongation and the growth of an apical tuft were accompanied by the formation of a faint annular groove. This groove marked off the definitive proboscis and the anterior part of the collar. Hatching followed 30 to 36 h after fertilization, and the larva became planktonic. During its lecithotrophic existence the larva developed a second annular groove anterior to the first, marking off the definitive proboscis from the anterior region of the collar. No definite phototaxis was detectable. Swimming movements were spasmodic. The larva rotated in a clockwise direction when viewed from the apical tuft. The spiral mode of propulsion and the propelling action of the telotroch is discussed. Settlement occurred some 2 days after hatching. A post-telotrochal adhesive patch was developed just prior to settlement, enabling the larva to adhere tenaciously to the substratum. After settlement further elongation of the main axis occurred, a well-defined proboscis, collar and trunk were rapidly differentiated. Of particular interest is the development of a long, muscular strongly ciliated post-anal tail. A dispersal period of about 612 to 7 days occurred prior to settlement. The existence of this phase prior to the animal adopting the adult mode of life demands that the mode of development of certain members of the family Harrimanidae be regarded as indirect and comparable in many respects to that known for some of the family Ptychoderidae. The mouth, anus and gill apertures became functional at much the same period, viz., at the onset of the burrowing phase. Remarkable growth movements initiated during the late planktonic phase were accelerated after settlement. This resulted in the translation of the telotroch to a latero-ventral position on the trunk and tail. The behaviour of the tail during the process of ciliary feeding, as well as during the coursing through the burrow, was observed. Ciliary reversal occurred on collar, trunk and tail. This phenomenon is discussed. Special tactile cilia have been described. They occurred on the dorsal and latero-dorsal surfaces of the trunk and tail. There was some evidence of gregariousness. The possibility of this larval habit is briefly considered in relation to the dispersal of the adults in the field. The homologies of the Enteropneusta and the Pterobranchia are discussed in some detail, with particular reference to the tail of the larval Saccoglossus horsti, and the stalk of the genus Cephalodiscus.

@article{burdonjones1952development,
    author = "Burdon-Jones, C.",
    title = "Development and Biology of the Larva of Saccoglossus Horsti (Enteropneusta)",
    year = "1952",
    journal = "Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences",
    abstract = "Larvae of Saccoglossus horsti were reared in the laboratory, and their developmental history from the egg to the five gill-slit stage studied. The immature eggs varied from 0.23 to 0.30 mm in length and from 0.15 to 0.22 mm in breadth. They were irregular, opaque, finely granular and creamish grey in colour. They became spherical on maturing. Fertilization resulted in the rapid erection of a fertilization membrane, making the eggs buoyant. Two similar polar bodies were extruded shortly afterwards, marking the plane of the first cleavage which, with the second, was holoblastic and meridional. Subsequent cleavages were different in the animal and vegetative tiers. There was evidence of radial cleavage during the 16- to 32-cell stage. A hollow blastula was formed at the 9th to 10th cleavage stage, and gastrulation by invagination followed. The blastocoele was completely obliterated and a typical archigastrula resulted. This rapidly became uniformly ciliated and developed a telotroch around the closing blastopore. The component cilia of the telotroch imparted a slow rotatory movement to the embryo. Axial elongation and the growth of an apical tuft were accompanied by the formation of a faint annular groove. This groove marked off the definitive proboscis and the anterior part of the collar. Hatching followed 30 to 36 h after fertilization, and the larva became planktonic. During its lecithotrophic existence the larva developed a second annular groove anterior to the first, marking off the definitive proboscis from the anterior region of the collar. No definite phototaxis was detectable. Swimming movements were spasmodic. The larva rotated in a clockwise direction when viewed from the apical tuft. The spiral mode of propulsion and the propelling action of the telotroch is discussed. Settlement occurred some 2 days after hatching. A post-telotrochal adhesive patch was developed just prior to settlement, enabling the larva to adhere tenaciously to the substratum. After settlement further elongation of the main axis occurred, a well-defined proboscis, collar and trunk were rapidly differentiated. Of particular interest is the development of a long, muscular strongly ciliated post-anal tail. A dispersal period of about 612 to 7 days occurred prior to settlement. The existence of this phase prior to the animal adopting the adult mode of life demands that the mode of development of certain members of the family Harrimanidae be regarded as indirect and comparable in many respects to that known for some of the family Ptychoderidae. The mouth, anus and gill apertures became functional at much the same period, viz., at the onset of the burrowing phase. Remarkable growth movements initiated during the late planktonic phase were accelerated after settlement. This resulted in the translation of the telotroch to a latero-ventral position on the trunk and tail. The behaviour of the tail during the process of ciliary feeding, as well as during the coursing through the burrow, was observed. Ciliary reversal occurred on collar, trunk and tail. This phenomenon is discussed. Special tactile cilia have been described. They occurred on the dorsal and latero-dorsal surfaces of the trunk and tail. There was some evidence of gregariousness. The possibility of this larval habit is briefly considered in relation to the dispersal of the adults in the field. The homologies of the Enteropneusta and the Pterobranchia are discussed in some detail, with particular reference to the tail of the larval Saccoglossus horsti, and the stalk of the genus Cephalodiscus.",
    url = "https://doi.org/10.1098/rstb.1952.0010",
    doi = "10.1098/rstb.1952.0010",
    number = "639",
    openalex = "W1994913686",
    pages = "553-589",
    volume = "236",
    references = "doi101242jcss282326227, openalexw605661459"
}

@article{burdonjones1953development2,
    author = "Burdon-Jones, C",
    title = "Development and biology of the larva of Saccoglossus horsti (Enteropnuesta)",
    year = "1953",
    journal = "Philosophical Transactions of the Royal Society, London B, v. 236, p. 553-589",
    note = "talkorigins\_source = {true}; raw\_reference = {Burdon-Jones, C., 1953, Development and biology of the larva of Saccoglossus horsti (Enteropnuesta): Philosophical Transactions of the Royal Society, London B, v. 236, p. 553-589.}"
}

Abstract Sparse and conflicting evidence concerning the mechanism and nature of developmental torsion and detorsion in the Opisthobranchia rendered necessary a full re-examination of these problems. Many contemporary general works either state or imply that during ontogeny opisthobranchs undergo 180° torsion (being identical with diotocardian prosobranchs in this respect) which is reversed in an unknown manner at some later stage of development. This theory is based on the work of Pelseneer (1911); the more detailed work of Saunders & Poole (1910) on Aplysia conflicts with Pelseneer’s views, but nevertheless these views have found wide currency. For this study, a species of dorid nudibranch, Adalaria proxima, was selected, for certain singular features of its biology rendered it possible to rear small populations through the com plete life cycle in the laboratory. A. proxima has an annual life cycle, the adults in nature dying after spawning, and their place being taken by the new generation of juvenile dorids. Death after spawning is correlated not with exhaustion of the germ cells, but with exhaustion of the food reserves built up in the pre-sexual phases of the life cycle. The species feeds mainly on an encrusting polyzoan, Electra pilosa, the dorid buccal pump playing an important part in the feeding mechanism. The spawn of Adalaria proxima shows the typical features characteristic of the egg masses of northern benthic invertebrates. The eggs are large, the number of eggs produced is small, the embryo hatches at a relatively advanced stage after a protracted em bryonic period. The early cleavage stages follow in all important respects the sequence and arrangement found in all dextrally organized gastropods. Gastrulation takes place by epiboly and the veliger form is rapidly assumed. Torsion in Adalaria is pushed back so far into development that it is no longer recognizable as a mechanical process. All the organs, as they become recognizable in sectioned postgastrulae, are arranged in the post-torsional positions, although the process of torsion has been halted far short of the full 180° found in living Diotocardia. The appearance of eyes, the development of the propodium and the structural and histological changes undergone by the mantle fold approximately 3 weeks after oviposition mark a departure from the pattern of embryonic development found in other species of dorid nudibranchs (Thompson 1957). Most of the organ systems are relatively greatly advanced in the hatching larva o Adalaria. The enlargement of the left midgut diverticulum brings about a slight rotation (continued during pelagic life) of the stomach; this is a process which is independent of torsion and was mentioned by Saunders & Poole, who, however, placed a slightly different interpretation upon it. Both dextral and sinistral components are present in the relations between the visceral and cephalopedal parts of the embryonic and larval body, but there can be no doubt that the dorids are truly dextral organisms. A complex arrangement of embryonic body cavities is present; it seems clear that the ‘coelom’ of Aplysia (Saunders & Poole 1910) corresponds to the inner perivisceral cavity of Adalaria, and that the term coelom in this connexion is a misnomer. The pelagic phase is divided into two distinct stages, during the first of which the larvae swim upwards, this behaviour being reversed at the start of the second stage. Searching behaviour characterizes the second stage alone, the selection of a suitable substrate for settlement being governed by an elaborate and highly specific sensory mechanism. Metamorphosis will only occur on a live colony of the encrusting polyzoan Electra pilosa. The cephalopedal ciliary apparatus directs a feeding current into the mouth; normal further development will, however, take place even in sterile sea-­water. The larval shell is a hyperstrophic one. Retraction of the larval body is brought about by the larval retractor muscle aided in a co-ordinatory capacity by contraction of muscular elements of the inner perivisceral membrane and of the cephalopedal subepidermal muscle complex. Metamorphosis involves drastic changes, but no change in basic orientation. Detorsion and reversal of visceral flexure are brought about in two stages as the mantle fold first becomes inverted and then spreads over the dorsal surface of the post-larva. The widely stated view that the dorsal integument of the adult dorid is the product o f the evolutionary enclosure of the shell by epipodial folds is contradicted by the embryological evidence. The larval retractor muscle disappears and the muscle complex of the adult is derived from the larval subepidermal muscle complex. The perivisceral cavities are obliterated and the adult haemocoel is derived from the larval cephalopedal subepidermal blastocoelic spaces. Calcareous spicules are laid down in the mantle. Concentration and fusion of the nerve ganglia result in a symmetrical arrangement, the embryonic system having shown traces of the ancestral streptoneury. A discussion of the nature of torsion in opisthobranchs almost entirely disagrees with the views of Pelseneer (1911). All the available evidence implies that torsion in opisthobranchs is greatly modified and never approaches the full 180° twisting found in living Diotocardia. It is not, of course, suggested that Pelseneer’s basic conclusion, that the prosobranchiate condition is ancestral to the opisthobranchiate, is in need of revision. Torsion in lying as it does at the extreme opposite end of the scale from the Diotocardia, is greatly modified and is no longer recognizable as a mechanical process; torsion in Adalaria does not occur for the same reasons as were important to the ancestral veliger, for in the dorids the larval mantle cavity does not serve to accommodate the head during retraction. The Suggestion is made that the usual manner of referring to torsion during development as involving a movement of the pallial complex from a posterior to an anterior position, is inaccurate and results from any attempt to describe ontogenetical torsion from the study of the adult gastropod alone. Finally, attention is drawn to the paradox that, although the dorid nudibranchs are the most highly evolved gastropods living (speaking in terms of gross structure), the com plex evolutionary steps which have led to the dorid have resulted in a secondary return, in many respects, to the original condition. In the adult dorid, only unimportant traces remain of the three most important steps in the structural evolution of the gastropods, visceral flexure, torsion, and bilateral asymmetry.

@article{doi101098rstb19580012,
    author = "Thompson, T. E.",
    title = "The natural history, embryology, larval biology and post-larval development of Adalaria proxima (Alder and Hancock) (Gastropoda Opisthobranchia)",
    year = "1958",
    journal = "Philosophical transactions of the Royal Society of London. Series B, Biological sciences",
    abstract = "Abstract Sparse and conflicting evidence concerning the mechanism and nature of developmental torsion and detorsion in the Opisthobranchia rendered necessary a full re-examination of these problems. Many contemporary general works either state or imply that during ontogeny opisthobranchs undergo 180° torsion (being identical with diotocardian prosobranchs in this respect) which is reversed in an unknown manner at some later stage of development. This theory is based on the work of Pelseneer (1911); the more detailed work of Saunders \& Poole (1910) on Aplysia conflicts with Pelseneer’s views, but nevertheless these views have found wide currency. For this study, a species of dorid nudibranch, Adalaria proxima, was selected, for certain singular features of its biology rendered it possible to rear small populations through the com plete life cycle in the laboratory. A. proxima has an annual life cycle, the adults in nature dying after spawning, and their place being taken by the new generation of juvenile dorids. Death after spawning is correlated not with exhaustion of the germ cells, but with exhaustion of the food reserves built up in the pre-sexual phases of the life cycle. The species feeds mainly on an encrusting polyzoan, Electra pilosa, the dorid buccal pump playing an important part in the feeding mechanism. The spawn of Adalaria proxima shows the typical features characteristic of the egg masses of northern benthic invertebrates. The eggs are large, the number of eggs produced is small, the embryo hatches at a relatively advanced stage after a protracted em bryonic period. The early cleavage stages follow in all important respects the sequence and arrangement found in all dextrally organized gastropods. Gastrulation takes place by epiboly and the veliger form is rapidly assumed. Torsion in Adalaria is pushed back so far into development that it is no longer recognizable as a mechanical process. All the organs, as they become recognizable in sectioned postgastrulae, are arranged in the post-torsional positions, although the process of torsion has been halted far short of the full 180° found in living Diotocardia. The appearance of eyes, the development of the propodium and the structural and histological changes undergone by the mantle fold approximately 3 weeks after oviposition mark a departure from the pattern of embryonic development found in other species of dorid nudibranchs (Thompson 1957). Most of the organ systems are relatively greatly advanced in the hatching larva o Adalaria. The enlargement of the left midgut diverticulum brings about a slight rotation (continued during pelagic life) of the stomach; this is a process which is independent of torsion and was mentioned by Saunders \& Poole, who, however, placed a slightly different interpretation upon it. Both dextral and sinistral components are present in the relations between the visceral and cephalopedal parts of the embryonic and larval body, but there can be no doubt that the dorids are truly dextral organisms. A complex arrangement of embryonic body cavities is present; it seems clear that the ‘coelom’ of Aplysia (Saunders \& Poole 1910) corresponds to the inner perivisceral cavity of Adalaria, and that the term coelom in this connexion is a misnomer. The pelagic phase is divided into two distinct stages, during the first of which the larvae swim upwards, this behaviour being reversed at the start of the second stage. Searching behaviour characterizes the second stage alone, the selection of a suitable substrate for settlement being governed by an elaborate and highly specific sensory mechanism. Metamorphosis will only occur on a live colony of the encrusting polyzoan Electra pilosa. The cephalopedal ciliary apparatus directs a feeding current into the mouth; normal further development will, however, take place even in sterile sea-­water. The larval shell is a hyperstrophic one. Retraction of the larval body is brought about by the larval retractor muscle aided in a co-ordinatory capacity by contraction of muscular elements of the inner perivisceral membrane and of the cephalopedal subepidermal muscle complex. Metamorphosis involves drastic changes, but no change in basic orientation. Detorsion and reversal of visceral flexure are brought about in two stages as the mantle fold first becomes inverted and then spreads over the dorsal surface of the post-larva. The widely stated view that the dorsal integument of the adult dorid is the product o f the evolutionary enclosure of the shell by epipodial folds is contradicted by the embryological evidence. The larval retractor muscle disappears and the muscle complex of the adult is derived from the larval subepidermal muscle complex. The perivisceral cavities are obliterated and the adult haemocoel is derived from the larval cephalopedal subepidermal blastocoelic spaces. Calcareous spicules are laid down in the mantle. Concentration and fusion of the nerve ganglia result in a symmetrical arrangement, the embryonic system having shown traces of the ancestral streptoneury. A discussion of the nature of torsion in opisthobranchs almost entirely disagrees with the views of Pelseneer (1911). All the available evidence implies that torsion in opisthobranchs is greatly modified and never approaches the full 180° twisting found in living Diotocardia. It is not, of course, suggested that Pelseneer’s basic conclusion, that the prosobranchiate condition is ancestral to the opisthobranchiate, is in need of revision. Torsion in lying as it does at the extreme opposite end of the scale from the Diotocardia, is greatly modified and is no longer recognizable as a mechanical process; torsion in Adalaria does not occur for the same reasons as were important to the ancestral veliger, for in the dorids the larval mantle cavity does not serve to accommodate the head during retraction. The Suggestion is made that the usual manner of referring to torsion during development as involving a movement of the pallial complex from a posterior to an anterior position, is inaccurate and results from any attempt to describe ontogenetical torsion from the study of the adult gastropod alone. Finally, attention is drawn to the paradox that, although the dorid nudibranchs are the most highly evolved gastropods living (speaking in terms of gross structure), the com plex evolutionary steps which have led to the dorid have resulted in a secondary return, in many respects, to the original condition. In the adult dorid, only unimportant traces remain of the three most important steps in the structural evolution of the gastropods, visceral flexure, torsion, and bilateral asymmetry.",
    url = "https://doi.org/10.1098/rstb.1958.0012",
    doi = "10.1098/rstb.1958.0012",
    openalex = "W2092184238"
}

@article{rocha1967biology,
    author = "Rocha, Aristides A.",
    title = "Biology and first instar larva of Epimetopus trogoides (Col., Hydrophilidae)",
    year = "1967",
    journal = "Papéis Avulsos de Zoologia",
    url = "https://doi.org/10.11606/0031-1049.1967.20p223-228",
    doi = "10.11606/0031-1049.1967.20p223-228",
    number = "1-21 (1967)",
    openalex = "W4394985563",
    pages = "223-228",
    volume = "20",
    references = "doi105962bhlpart24391, doi105962bhltitle60200"
}

Abstract The newly hatched Müller’s larva of the polyclad Pseudoceros canadensis is described at the electron microscopical level with attention to the arrangement and innervation of the ciliary band and the organization of the larval nervous system. Distinctive ultrastructural features allow the trochal cells of the band to be distinguished from general epithelium of the body surface and the specialized oral field epithelium. The band comprises a ventral and a dorsal marginal loop that run along the margins of the six projecting lobes of the larva, and a suboral plate that forms a bridge between these behind the mouth. These three components are joined asymmetrically to form a single, but discontinuous, band: on the left the ventral loop and suboral plate are joined, but these fail to connect with the dorsal loop; on the right it is the ventral and dorsal loops that join, but there is no connection between these and the suboral plate. A system of intraepithelial nerves is associated with the ciliary band, the largest nerves being those in the ventrolateral lobes and the intraepithelial commissure that connects these across the oral field. The system is truly peripheral: it lies outside the basement membrane and is separated by it from the central nervous system, which at this stage comprises a brain and four radiating nerve cords. The peripheral and central nervous systems are in direct contact only at two points, located just behind the ventrolateral lobes on either side of the larva, where a few neurites pass through the basement membrane from one system to the other. The neurites of the peripheral system arise mainly from bipolar sensory cells located in the ciliary band. These are concentrated along the ventrolateral lobes, and their projecting cilia face incoming water currents. Observations on larval swimming behaviour do not, however, suggest any obvious function for these cells. The ciliary band is thus organized as a self-contained unit supplying its own innervation. Other primitive invertebrate larvae have ciliary bands that are similar to some extent in their organization and ultra­structure. This, added to what is already known about Müller’s larva, supports the idea that it is primitive and is closely related to at least several other larval types, but it is not clear how the overall arrangement of the band in Müller’s larva as described here relates to what is seen in other larvae. Several ways in which the pattern might have originated from simpler patterns in hypothetical ancestral forms are, however, discussed.

@article{doi101098rspb19820093,
    author = "Lacalli, Thurston C.",
    title = "The nervous system and ciliary band of Müller’s larva",
    year = "1982",
    journal = "Proceedings of the Royal Society of London. Series B, Biological sciences",
    abstract = "Abstract The newly hatched Müller’s larva of the polyclad Pseudoceros canadensis is described at the electron microscopical level with attention to the arrangement and innervation of the ciliary band and the organization of the larval nervous system. Distinctive ultrastructural features allow the trochal cells of the band to be distinguished from general epithelium of the body surface and the specialized oral field epithelium. The band comprises a ventral and a dorsal marginal loop that run along the margins of the six projecting lobes of the larva, and a suboral plate that forms a bridge between these behind the mouth. These three components are joined asymmetrically to form a single, but discontinuous, band: on the left the ventral loop and suboral plate are joined, but these fail to connect with the dorsal loop; on the right it is the ventral and dorsal loops that join, but there is no connection between these and the suboral plate. A system of intraepithelial nerves is associated with the ciliary band, the largest nerves being those in the ventrolateral lobes and the intraepithelial commissure that connects these across the oral field. The system is truly peripheral: it lies outside the basement membrane and is separated by it from the central nervous system, which at this stage comprises a brain and four radiating nerve cords. The peripheral and central nervous systems are in direct contact only at two points, located just behind the ventrolateral lobes on either side of the larva, where a few neurites pass through the basement membrane from one system to the other. The neurites of the peripheral system arise mainly from bipolar sensory cells located in the ciliary band. These are concentrated along the ventrolateral lobes, and their projecting cilia face incoming water currents. Observations on larval swimming behaviour do not, however, suggest any obvious function for these cells. The ciliary band is thus organized as a self-contained unit supplying its own innervation. Other primitive invertebrate larvae have ciliary bands that are similar to some extent in their organization and ultra­structure. This, added to what is already known about Müller’s larva, supports the idea that it is primitive and is closely related to at least several other larval types, but it is not clear how the overall arrangement of the band in Müller’s larva as described here relates to what is seen in other larvae. Several ways in which the pattern might have originated from simpler patterns in hypothetical ancestral forms are, however, discussed.",
    url = "https://doi.org/10.1098/rspb.1982.0093",
    doi = "10.1098/rspb.1982.0093",
    openalex = "W2009169318",
    references = "doi101007bf00222422, doi101139z78290"
}

@article{bisgrove1987development,
    author = "Bisgrove, BrentW. and Burke, RobertD.",
    title = "Development of the nervous system of the pluteus larva of Strongylocentrotus droebachiensis",
    year = "1987",
    journal = "Cell and Tissue Research",
    url = "https://doi.org/10.1007/bf00218200",
    doi = "10.1007/bf00218200",
    number = "2",
    openalex = "W2089208330",
    volume = "248",
    references = "doi101002jez1401990212, doi101007bf00222422, doi1010160022098171900542, doi1010160022098180900404, doi101093icb153717, doi101098rstb19030006, doi101111j1440169x198600569x, doi101126science7433992, doi1023071540409, openalexw2151348630"
}

@article{nicol1988development,
    author = "Nicol, D. and Meinertzhagen, I.A.",
    title = "Development of the central nervous system of the larva of the ascidian, Ciona intestinalis L",
    year = "1988",
    journal = "Developmental Biology",
    url = "https://doi.org/10.1016/0012-1606(88)90364-8",
    doi = "10.1016/0012-1606(88)90364-8",
    number = "2",
    openalex = "W1547999461",
    pages = "737-766",
    volume = "130",
    references = "doi101002cne900620207, doi101002jez1400020202, doi1010160012160677901580, doi101016001216068090353x, doi1010160012160683902014, doi1010160012160687901886, doi101017cbo9780511897948, doi101098rstb19350013, doi101098rstb19860056, doi1023071439568, doi105962bhltitle4801"
}

@article{michaeld1991nervous,
    author = "Michael D., Gershon",
    title = "Nervous system development: Functional differentiation of neural cells",
    year = "1991",
    journal = "Journal of Neuroimmunology",
    url = "https://doi.org/10.1016/0165-5728(91)90835-u",
    doi = "10.1016/0165-5728(91)90835-u",
    openalex = "W2120898536",
    pages = "4",
    volume = "35"
}

@article{chayapum1993proliferating,
    author = "Chayapum, Pracha",
    title = "Proliferating acephalic cestode larva of central nervous system",
    year = "1993",
    journal = "Chulalongkorn Medical Journal",
    url = "https://doi.org/10.58837/chula.cmj.37.12.6",
    doi = "10.58837/chula.cmj.37.12.6",
    number = "12",
    openalex = "W4391115418",
    pages = "743-743",
    volume = "37"
}

The present immunocytochemical study utilizes serotonin and SALMFamide antisera, together with confocal laser scanning microscopy, to provide new information about the development of the nervous system in the sea urchin Psammechinus miliaris (Echinodermata: Echinoidea). Special attention is paid to the extent of the nervous system in later larval stages (6-armed pluteus to metamorphic competency), a characteristic that has not been well described in this and other species of sea urchin. An extensive apical ganglion appears by the 6-armed pluteus stage, forming a complex of 10-20 cells and fibers, including discrete populations of both serotonin-like and SALMF-amide-like immunoreactive cells. At metamorphosis this complex is large, comprising at least 40 cells in distinct arrays. Serotonin-like immunoreactivity is also particularly apparent in the lower lip ganglion of 6- to 8-armed plutei; this ganglion consists of 15-18 cells that are distributed around the mouth. The ciliary nerves that lie beneath the ciliary bands in the larval arms, the esophagus, and a hitherto undescribed network associated with the pylorus all show SALMFamide-like immunoreactivity. The network of cells and fibers in the pyloric area develops later in larval life. It first appears as one cell body and fiber, then increases in size and complexity through the 8-armed pluteus stage to form a complex of cells that encircles the pylorus. SALMFamide-like, but not serotonin-like, immunoreactivity is seen in the vestibule wall, tube feet, and developing radial nerve fibers of the sea urchin adult rudiment as the larva gains metamorphic competency.

@article{doi1023071543509,
    author = "Beer, Amy-Jane and Moss, Claire and Thorndyke, Michael C.",
    title = "Development of Serotonin-like and SALMFamide-like Immunoreactivity in the Nervous System of the Sea Urchin Psammechinus miliaris",
    year = "2001",
    journal = "Biological Bulletin",
    abstract = "The present immunocytochemical study utilizes serotonin and SALMFamide antisera, together with confocal laser scanning microscopy, to provide new information about the development of the nervous system in the sea urchin Psammechinus miliaris (Echinodermata: Echinoidea). Special attention is paid to the extent of the nervous system in later larval stages (6-armed pluteus to metamorphic competency), a characteristic that has not been well described in this and other species of sea urchin. An extensive apical ganglion appears by the 6-armed pluteus stage, forming a complex of 10-20 cells and fibers, including discrete populations of both serotonin-like and SALMF-amide-like immunoreactive cells. At metamorphosis this complex is large, comprising at least 40 cells in distinct arrays. Serotonin-like immunoreactivity is also particularly apparent in the lower lip ganglion of 6- to 8-armed plutei; this ganglion consists of 15-18 cells that are distributed around the mouth. The ciliary nerves that lie beneath the ciliary bands in the larval arms, the esophagus, and a hitherto undescribed network associated with the pylorus all show SALMFamide-like immunoreactivity. The network of cells and fibers in the pyloric area develops later in larval life. It first appears as one cell body and fiber, then increases in size and complexity through the 8-armed pluteus stage to form a complex of cells that encircles the pylorus. SALMFamide-like, but not serotonin-like, immunoreactivity is seen in the vestibule wall, tube feet, and developing radial nerve fibers of the sea urchin adult rudiment as the larva gains metamorphic competency.",
    url = "https://doi.org/10.2307/1543509",
    doi = "10.2307/1543509",
    openalex = "W2097178659"
}

The programmed cell death (PCD) of developing cells is considered an essential adaptive process that evolved to serve diverse roles. We review the putative adaptive functions of PCD in the animal kingdom with a major focus on PCD in the developing nervous system. Considerable evidence is consistent with the role of PCD in events ranging from neurulation and synaptogenesis to the elimination of adult-generated CNS cells. The remarkable recent progress in our understanding of the genetic regulation of PCD has made it possible to perturb (inhibit) PCD and determine the possible repercussions for nervous system development and function. Although still in their infancy, these studies have so far revealed few striking behavioral or functional phenotypes.

@article{doi101146annurevneuro29051605112800,
    author = "Buss, Robert R. and Sun, Woong and Oppenheim, Ronald W.",
    title = "ADAPTIVE ROLES OF PROGRAMMED CELL DEATH DURING NERVOUS SYSTEM DEVELOPMENT",
    year = "2006",
    journal = "Annual Review of Neuroscience",
    abstract = "The programmed cell death (PCD) of developing cells is considered an essential adaptive process that evolved to serve diverse roles. We review the putative adaptive functions of PCD in the animal kingdom with a major focus on PCD in the developing nervous system. Considerable evidence is consistent with the role of PCD in events ranging from neurulation and synaptogenesis to the elimination of adult-generated CNS cells. The remarkable recent progress in our understanding of the genetic regulation of PCD has made it possible to perturb (inhibit) PCD and determine the possible repercussions for nervous system development and function. Although still in their infancy, these studies have so far revealed few striking behavioral or functional phenotypes.",
    url = "https://doi.org/10.1146/annurev.neuro.29.051605.112800",
    doi = "10.1146/annurev.neuro.29.051605.112800",
    openalex = "W2154352037",
    references = "nicol1988development"
}

The ascidian chordate Ciona intestinalis is an established model organism frequently exploited to examine cellular development and a rapidly emerging model organism with a strong potential for developmental systems biology studies. However, there is no standardized developmental table for this organism. In this study, we made the standard web-based image resource called FABA: Four-dimensional Ascidian Body Atlas including ascidian's three-dimensional (3D) and cross-sectional images through the developmental time course. These images were reconstructed from more than 3,000 high-resolution real images collected by confocal laser scanning microscopy (CLSM) at newly defined 26 distinct developmental stages (stages 1-26) from fertilized egg to hatching larva, which were grouped into six periods named the zygote, cleavage, gastrula, neurula, tailbud, and larva periods. Our data set will be helpful in standardizing developmental stages for morphology comparison as well as for providing the guideline for several functional studies of a body plan in chordate.

@article{doi101002dvdy21188,
    author = "Hotta, Kohji and Mitsuhara, Kenta and Takahashi, Hiroki and Inaba, Kazuo and Oka, Kotaro and Gojobori, Takashi and Ikeo, Kazuho",
    title = "A web‐based interactive developmental table for the ascidian Ciona intestinalis, including 3D real‐image embryo reconstructions: I. From fertilized egg to hatching larva",
    year = "2007",
    journal = "Developmental Dynamics",
    abstract = "The ascidian chordate Ciona intestinalis is an established model organism frequently exploited to examine cellular development and a rapidly emerging model organism with a strong potential for developmental systems biology studies. However, there is no standardized developmental table for this organism. In this study, we made the standard web-based image resource called FABA: Four-dimensional Ascidian Body Atlas including ascidian's three-dimensional (3D) and cross-sectional images through the developmental time course. These images were reconstructed from more than 3,000 high-resolution real images collected by confocal laser scanning microscopy (CLSM) at newly defined 26 distinct developmental stages (stages 1-26) from fertilized egg to hatching larva, which were grouped into six periods named the zygote, cleavage, gastrula, neurula, tailbud, and larva periods. Our data set will be helpful in standardizing developmental stages for morphology comparison as well as for providing the guideline for several functional studies of a body plan in chordate.",
    url = "https://doi.org/10.1002/dvdy.21188",
    doi = "10.1002/dvdy.21188",
    openalex = "W2094577119",
    references = "nicol1988development"
}

Ripe specimens of Ptychodera flava were collected at Paiko Peninsula, Oahu, Hawaii, USA, and the development from egg to tornaria larva was followed in the laboratory. To complete the series, large tornaria larvae were collected from the plankton off the nearby Ala Moana Beach, and followed through metamorphosis to a juvenile stage with four pairs of gill slits. Ciliary band development was examined by scanning electron microscopy, and the development of the serotonergic nervous system was followed by means of immunostaining. The development of the apical tuft and neotroch (circumoral/perioral ciliary band) and their subsequent degeneration accorded fully with previous descriptions. A perianal ciliary ring of separate cilia develops just after hatching. This later develops a midventral extension, the neurotroch, extending to the neotroch posterior to the mouth. The cilia of this ring apparently beat diaplectically, with the effective stroke in the clockwise direction when seen from behind. An additional ring of cilia develops several days later anterior to the perianal ring. This opisthotroch (called telotroch by previous authors) consists at first of separate cilia, but later they became organized as large compound cilia. The apical tuft disappears after about a week, the neotroch degenerates at the transition to the Agassiz stage, and the opisthotroch degenerates just after metamorphosis. The serotonergic nervous system of the fully grown tornaria consists of an apical ganglion with many perikarya, a paired lateral group of perikarya on the postoral ciliary band, and scattered perikarya along the opisthotroch. Serotonergic processes are found along the ciliary bands except for the ventral and perianal ciliary bands and are scattered along the epidermis. At the Spengel stage and at metamorphosis (Agassiz stage), the processes along the ciliary bands are concentrated in the three ciliated food grooves so as to form three separate nerves, and are retained on the proboscis at least until 2-3 gill slit stage. No serotonergic processes were found to extend from the proboscis to the collar region, and no serotonergic neurons were observed in the collar cord or in the ventral nerve cord. Our results therefore do not provide any clues as to the origin of the chordate neural tube relative to the dorsal-ventral orientation of the enteropneusts.

@article{doi101002jmor10533,
    author = "Nielsen, Claus and Hay‐Schmidt, Anders",
    title = "Development of the enteropneust Ptychodera flava: Ciliary bands and nervous system",
    year = "2007",
    journal = "Journal of Morphology",
    abstract = "Ripe specimens of Ptychodera flava were collected at Paiko Peninsula, Oahu, Hawaii, USA, and the development from egg to tornaria larva was followed in the laboratory. To complete the series, large tornaria larvae were collected from the plankton off the nearby Ala Moana Beach, and followed through metamorphosis to a juvenile stage with four pairs of gill slits. Ciliary band development was examined by scanning electron microscopy, and the development of the serotonergic nervous system was followed by means of immunostaining. The development of the apical tuft and neotroch (circumoral/perioral ciliary band) and their subsequent degeneration accorded fully with previous descriptions. A perianal ciliary ring of separate cilia develops just after hatching. This later develops a midventral extension, the neurotroch, extending to the neotroch posterior to the mouth. The cilia of this ring apparently beat diaplectically, with the effective stroke in the clockwise direction when seen from behind. An additional ring of cilia develops several days later anterior to the perianal ring. This opisthotroch (called telotroch by previous authors) consists at first of separate cilia, but later they became organized as large compound cilia. The apical tuft disappears after about a week, the neotroch degenerates at the transition to the Agassiz stage, and the opisthotroch degenerates just after metamorphosis. The serotonergic nervous system of the fully grown tornaria consists of an apical ganglion with many perikarya, a paired lateral group of perikarya on the postoral ciliary band, and scattered perikarya along the opisthotroch. Serotonergic processes are found along the ciliary bands except for the ventral and perianal ciliary bands and are scattered along the epidermis. At the Spengel stage and at metamorphosis (Agassiz stage), the processes along the ciliary bands are concentrated in the three ciliated food grooves so as to form three separate nerves, and are retained on the proboscis at least until 2-3 gill slit stage. No serotonergic processes were found to extend from the proboscis to the collar region, and no serotonergic neurons were observed in the collar cord or in the ventral nerve cord. Our results therefore do not provide any clues as to the origin of the chordate neural tube relative to the dorsal-ventral orientation of the enteropneusts.",
    url = "https://doi.org/10.1002/jmor.10533",
    doi = "10.1002/jmor.10533",
    openalex = "W2009040920",
    references = "burdonjones1952development, doi101002jezb20001, doi101016s0092867403004690, doi101038371026a0, doi101046j13652109200300819x, doi101098rspb20001111, doi101111j146363951987tb00892x, doi101242dev126185, doi101242jcss27228551, doi101371journalpbio0040291, doi105860choice501469"
}

@misc{crossref2010menkia,
    title = "Menkia horsti: Gómez, B.",
    year = "2010",
    booktitle = "IUCN Red List of Threatened Species",
    url = "https://doi.org/10.2305/iucn.uk.2011-1.rlts.t156631a4976000.en",
    doi = "10.2305/iucn.uk.2011-1.rlts.t156631a4976000.en",
    openalex = "W4254104109"
}

@misc{crossref2010procambarus,
    title = "Procambarus horsti: Crandall, K.A.",
    year = "2010",
    booktitle = "IUCN Red List of Threatened Species",
    url = "https://doi.org/10.2305/iucn.uk.2010-3.rlts.t18201a7786330.en",
    doi = "10.2305/iucn.uk.2010-3.rlts.t18201a7786330.en",
    openalex = "W4242531658"
}

Recent studies of the sea urchin embryo have elucidated the mechanisms that localize and pattern its nervous system. These studies have revealed the presence of two overlapping regions of neurogenic potential at the beginning of embryogenesis, each of which becomes progressively restricted by separate, yet linked, signals, including Wnt and subsequently Nodal and BMP. These signals act to specify and localize the embryonic neural fields - the anterior neuroectoderm and the more posterior ciliary band neuroectoderm - during development. Here, we review these conserved nervous system patterning signals and consider how the relationships between them might have changed during deuterostome evolution.

@article{doi101242dev058172,
    author = "Angerer, Lynne M. and Yaguchi, Shunsuke and Angerer, Robert C. and Burke, Robert D.",
    title = "The evolution of nervous system patterning: insights from sea urchin development",
    year = "2011",
    journal = "Development",
    abstract = "Recent studies of the sea urchin embryo have elucidated the mechanisms that localize and pattern its nervous system. These studies have revealed the presence of two overlapping regions of neurogenic potential at the beginning of embryogenesis, each of which becomes progressively restricted by separate, yet linked, signals, including Wnt and subsequently Nodal and BMP. These signals act to specify and localize the embryonic neural fields - the anterior neuroectoderm and the more posterior ciliary band neuroectoderm - during development. Here, we review these conserved nervous system patterning signals and consider how the relationships between them might have changed during deuterostome evolution.",
    url = "https://doi.org/10.1242/dev.058172",
    doi = "10.1242/dev.058172",
    openalex = "W2137646798",
    references = "doi101016jcub200905063, doi101016jydbio201005016, doi101093icb153717, doi101111j1440169x198600569x, doi101111j1525142x200404011x"
}

BACKGROUND: Larval features such as the apical organ, apical ciliary tuft, and ciliated bands often complicate the evaluation of hypotheses regarding the origin of the adult bilaterian nervous system. Understanding how neurogenic domains form within the bilaterian head and larval apical organ requires expression data from animals that exhibit aspects of both centralized and diffuse nervous systems at different life history stages. Here, we describe the expression of eight neural-related genes during the larval development of the brachiopod, Terebratalia transversa. RESULTS: Radially symmetric gastrulae broadly express Tt-Six3/6 and Tt-hbn in the animal cap ectoderm. Tt-NK2.1 and Tt-otp are restricted to a central subset of these cells, and Tt-fez and Tt-FoxQ2 expression domains are already asymmetric at this stage. As gastrulation proceeds, the spatial expression of these genes is split between two anterior ectodermal domains, a more dorsal region comprised of Tt-Six3/6, Tt-fez, Tt-FoxQ2, and Tt-otp expression domains, and an anterior ventral domain demarcated by Tt-hbn and Tt-NK2.1 expression. More posteriorly, the latter domains are bordered by Tt-FoxG expression in the region of the transverse ciliated band. Tt-synaptotagmin 1 is expressed throughout the anterior neural ectoderm. All genes are expressed late into larval development. The basiepithelial larval nervous system includes three neurogenic domains comprised of the more dorsal apical organ and a ventral cell cluster in the apical lobe as well as a mid-ventral band of neurons in the mantle lobe. Tt-otp is the only gene expressed in numerous flask-shaped cells of the apical organ and in a subset of neurons in the mantle lobe. CONCLUSIONS: Our expression data for Tt-Six3/6, Tt-FoxQ2, and Tt-otp confirm some aspects of bilaterian-wide conservation of spatial partitioning within anterior neurogenic domains and also suggest a common origin for central otp-positive cell types within the larval apical organs of spiralians. However, the field of sensory neurons within the larval apical organ of Terebratalia is broader and composed of more cells relative to those of other spiralian larvae. These cellular differences are mirrored in the broader spatial and temporal expression patterns of Tt-FoxQ2 and Tt-otp. Corresponding differences in the expression of Tt-hbn, Tt-NK2.1, and Tt-FoxG are also observed relative to their respective domains within the cerebral ganglia of spiralians. Based on these data we argue that the anterior region of the bilaterian stem species included Six3/6, NK2.1, otp, hbn, fez, and FoxQ2 expression domains that were subsequently modified within larval and adult neural tissues of protostome and deuterostome animals.

@article{doi1011862041913933,
    author = "Santagata, Scott and Resh, Carlee and Hejnol, Andreas and Martindale, Mark Q. and Passamaneck, Yale J.",
    title = "Development of the larval anterior neurogenic domains of Terebratalia transversa (Brachiopoda) provides insights into the diversification of larval apical organs and the spiralian nervous system",
    year = "2012",
    journal = "EvoDevo",
    abstract = "BACKGROUND: Larval features such as the apical organ, apical ciliary tuft, and ciliated bands often complicate the evaluation of hypotheses regarding the origin of the adult bilaterian nervous system. Understanding how neurogenic domains form within the bilaterian head and larval apical organ requires expression data from animals that exhibit aspects of both centralized and diffuse nervous systems at different life history stages. Here, we describe the expression of eight neural-related genes during the larval development of the brachiopod, Terebratalia transversa. RESULTS: Radially symmetric gastrulae broadly express Tt-Six3/6 and Tt-hbn in the animal cap ectoderm. Tt-NK2.1 and Tt-otp are restricted to a central subset of these cells, and Tt-fez and Tt-FoxQ2 expression domains are already asymmetric at this stage. As gastrulation proceeds, the spatial expression of these genes is split between two anterior ectodermal domains, a more dorsal region comprised of Tt-Six3/6, Tt-fez, Tt-FoxQ2, and Tt-otp expression domains, and an anterior ventral domain demarcated by Tt-hbn and Tt-NK2.1 expression. More posteriorly, the latter domains are bordered by Tt-FoxG expression in the region of the transverse ciliated band. Tt-synaptotagmin 1 is expressed throughout the anterior neural ectoderm. All genes are expressed late into larval development. The basiepithelial larval nervous system includes three neurogenic domains comprised of the more dorsal apical organ and a ventral cell cluster in the apical lobe as well as a mid-ventral band of neurons in the mantle lobe. Tt-otp is the only gene expressed in numerous flask-shaped cells of the apical organ and in a subset of neurons in the mantle lobe. CONCLUSIONS: Our expression data for Tt-Six3/6, Tt-FoxQ2, and Tt-otp confirm some aspects of bilaterian-wide conservation of spatial partitioning within anterior neurogenic domains and also suggest a common origin for central otp-positive cell types within the larval apical organs of spiralians. However, the field of sensory neurons within the larval apical organ of Terebratalia is broader and composed of more cells relative to those of other spiralian larvae. These cellular differences are mirrored in the broader spatial and temporal expression patterns of Tt-FoxQ2 and Tt-otp. Corresponding differences in the expression of Tt-hbn, Tt-NK2.1, and Tt-FoxG are also observed relative to their respective domains within the cerebral ganglia of spiralians. Based on these data we argue that the anterior region of the bilaterian stem species included Six3/6, NK2.1, otp, hbn, fez, and FoxQ2 expression domains that were subsequently modified within larval and adult neural tissues of protostome and deuterostome animals.",
    url = "https://doi.org/10.1186/2041-9139-3-3",
    doi = "10.1186/2041-9139-3-3",
    openalex = "W2099103639",
    references = "doi101002jmor10533"
}

@misc{crossref2022menkia,
    title = "Menkia horsti: Gómez-Moliner, B.J.",
    year = "2022",
    booktitle = "IUCN Red List of Threatened Species",
    url = "https://doi.org/10.2305/iucn.uk.2025-2.rlts.t156631a220178589.en",
    doi = "10.2305/iucn.uk.2025-2.rlts.t156631a220178589.en",
    openalex = "W4415808906"
}