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Eckelbarger KJ, Hodgson AN. Invertebrate oogenesis – a review and synthesis: comparative ovarian morphology, accessory cell function and the origins of yolk precursors. INVERTEBR REPROD DEV 2021. [DOI: 10.1080/07924259.2021.1927861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Kevin J. Eckelbarger
- Darling Marine Center, School of Marine Sciences, The University of Maine, Walpole, Maine, U.S.A
| | - Alan N. Hodgson
- Department of Zoology and Entomology, Rhodes University, Grahamstown, South Africa
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2
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Eisenman EA, Alfert M. A new fixation procedure for preserving the ultrastructure of marine invertebrate tissues. J Microsc 2011. [DOI: 10.1111/j.1365-2818.1982.tb00327.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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3
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Ozeki Y, Tazawa E, Matsui T. D-galactoside-specific lectins from the body wall of an echiuroid (Urechis unicinctus) and two annelids (Neanthes japonica and Marphysa sanguinea). Comp Biochem Physiol B Biochem Mol Biol 1997; 118:1-6. [PMID: 9417987 DOI: 10.1016/s0305-0491(97)00014-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Lectins recognizing D-galactosides were purified from the body wall of an echiuroid; Urechis unicinctus and two annelids; Neanthes japonica and Marphysa sanguinea, with single step lactosyl-agarose affinity column chromatography. SDS-PAGE under reduced and non-reduced conditions showed that U. unicinctus lectin had a major (36 kDa) and two minor (40 and 14 kDa) proteins, and that N. japonica lectin and M. sanguinea lectin had single 33 and 35 kDa proteins, respectively. Lectins were solubilized in the presence of lactose from tissues, and all polypeptides were shown to have sugar binding activity. The antisera raised against U. unicinctus lectin and N. japonica lectin crossreacted with each other but did not crossreact with bull frog (Rana catesbeiana) egg galectin-1 or a D-galactoside-specific lectin purified from sea urchin (Anthocidaris crassispina) eggs. These echiuroid and annelid lectins are immunologically similar, but distinct from members of the vertebrate galectin family.
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Affiliation(s)
- Y Ozeki
- Department of System Element, Faculty of Science, Yokohama City University, Japan
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GOULD MEREDITHC, STEPHANO JOSÉLUIS. Fertilization and parthenogenesis inUrechis caupo(Echiura). INVERTEBR REPROD DEV 1996. [DOI: 10.1080/07924259.1996.9672527] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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5
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Peavy TR, Carroll EJ. The Primary Egg Envelope of the Anuran Lepidobatrachus laevis: Physicochemical and Macromolecular Alterations During Development. (egg envelopes). Dev Growth Differ 1993. [DOI: 10.1111/j.1440-169x.1993.00447.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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6
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Kessel RG. Annulate lamellae: a last frontier in cellular organelles. INTERNATIONAL REVIEW OF CYTOLOGY 1992; 133:43-120. [PMID: 1374369 DOI: 10.1016/s0074-7696(08)61858-6] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- R G Kessel
- Department of Biology, University of Iowa, Iowa City 52242
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7
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Holland ND, Grimmer JC, Wiegmann K. The structure of the sea lilyCalamocrinus diomedae, with special reference to the articulations, skeletal microstructure, symbiotic bacteria, axial organs, and stalk tissues (Crinoida, Millericrinida). ZOOMORPHOLOGY 1991. [DOI: 10.1007/bf01632868] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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8
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Carroll EJ, Wei SH, Nagel GM, Ruibal R. Structure and Macromolecular Composition of the Egg and Embryo Jelly Coats of the Anuran Lepidobatrachus laevis. (frog jelly coat/fertilization/glycoprotein). Dev Growth Differ 1991. [DOI: 10.1111/j.1440-169x.1991.00037.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Carroll EJ, Cohen JS. A comparison of fertilization envelope development in three species of Strongylocentrotus (S. franciscanus, S. droebachiensis, and S. purpuratus). Mol Reprod Dev 1990; 25:77-86. [PMID: 2393586 DOI: 10.1002/mrd.1080250114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The ultrastructure of fertilization envelope (FE) development and the polypeptide spectra of Strongylocentrotus franciscanus and S. droebachiensis envelopes were compared to S. purpuratus. In S. franciscanus, the FE reached its maximum thickness of 67 nm by 3 minutes postinsemination (PI), and final structuralization was observed by 40 minutes PI. The fully formed FE did not have microvillar impressions (casts) and was symmetrical, with outer double laminar elements surrounding an amorphous central region. Isolated S. franciscanus FEs were soluble in reducing and denaturing solvents and the same set of 33 polypeptides ranging from 18.5 to 260 kD was detected in FEs isolated from 10 to 180 minutes PI. The S. droebachiensis FE retained microvillar casts, assumed its definitive form by 3 minutes PI, and was 70 nm thick between microvillar impressions. Isolated S. droebachiensis FEs were partially soluble in reducing and denaturing solvents, and the polypeptide spectra of FEs isolated between 10 and 60 minutes PI were identical and showed 14 polypeptides from 18.5 to 265 kD. Antisera against extracted FEs and the FE extract from S. purpuratus were immunologically cross-reactive (using an enzyme-linked immunosorbent assay) with S. franciscanus and S. droebachiensis FE preparations; immunoblots identified 13 and 5 cross-reactive polypeptides, respectively. Most of the cross-reactive polypeptides were of slightly different molecular weight. Based on comparative ultrastructural, solubility, and electrophoretic data, we suggest that S. droebachiensis FE development is most like that observed in S. purpuratus.
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Affiliation(s)
- E J Carroll
- Department of Biology, University of California, Riverside 92521
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10
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Abstract
This review aims to provide a comprehensive and in-depth survey of a cell organelle, the annulate lamellae, that is widely distributed and especially prevalent in both female and male sex cells as well as tumor and cancer cells. The organelle is also present in many somatic cells and plant cells. Emphasis is placed on the contributions that electron microscopy and associated experimental approaches have made in providing information about the distribution, ultrastructure, morphogenesis and relationships of annulate lamellae to other cellular organelles, especially the nuclear envelope and endoplasmic reticulum, as well as cell product. An increasing number of experimental manipulations have recently been shown to alter, either increase or decrease, the amount of annulate lamellae and these studies are explored in depth. Information about the origin and morphogenesis of annulate lamellae in different cells is summarized and extensive coverage is given to several hypotheses about possible annulate lamellae function. A detailed bibliography provides a thorough compilation of research dealing with annulate lamellae. A major goal of this extensive review is to generate increased awareness of, and interest in, this cell organelle for students and investigators of the cell who, by bringing current techniques in cell and molecular biology to bear, might focus and intensify studies on the function of an organelle whose precise role in the cell is presently enigmatic.
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11
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Fertilization in Oikopleura dioica (Tunicata, Appendicularia): Acrosome reaction, cortical reaction and sperm-egg fusion. ZOOMORPHOLOGY 1988. [DOI: 10.1007/bf00312223] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Holland LZ. Spermatogenesis in the salpsThalia democratica andCyclosalpa affinis (Tunicata: Thaliacea): An electron microscopic study. J Morphol 1988; 198:189-204. [DOI: 10.1002/jmor.1051980206] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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13
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Gould M, Stephano J, Holland LZ. Isolation of protein from Urechis sperm acrosomal granules that binds sperm to eggs and initiates development. Dev Biol 1986. [DOI: 10.1016/0012-1606(86)90373-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Sato M, Osani K. Morphological identification of sperm receptors above egg microvilli in the polychaete, Neanthes japonica. Dev Biol 1986; 113:263-70. [PMID: 3005089 DOI: 10.1016/0012-1606(86)90161-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A fine-structural study of sperm-egg interactions in the polychaete Neanthes japonica was carried out. Unfertilized eggs are surrounded by a chorion 0.6-0.7 micrometers thick. Oocyte microvilli are inserted into the inner layer of the chorion. The outer layers of the chorion are opened just above the tips of the microvilli, where a membrane vesicle (microvillus tip vesicle, about 0.2 micrometers in diameter) plugs the chorion's opening. During fertilization, the acrosomal process of the sperm fuses with an egg microvillus within 1 min of insemination. All the microvillus tip vesicles disappear from the chorion surface within 5 min of insemination. When eggs, which are prefixed with glutaraldehyde, are inseminated, numerous sperm undergoing the acrosome reactions attach to the eggs. In the majority of these sperm, the tip of acrosomal process which is coated with the acrosomal content, adhere to a microvillus tip vesicle. These findings suggest that the microvillus tip vesicle serves as a sperm receptor, which induces the acrosome reactions and adhere to the sperm acrosomal process. The adhesion of the acrosomal process to the microvillus tip vesicle seems to be a prerequisite event for its fusion with the microvillus.
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Carroll EJ, Acevedo-Duncan M, Justice RW, Santiago L. Structure, assembly and function of the surface envelope (fertilization envelope) from eggs of the sea urchin, Strongylocentrotus purpuratus. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1986; 207:261-91. [PMID: 3548240 DOI: 10.1007/978-1-4613-2255-9_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The sea urchin fertilization envelope (FE) is formed following initial sperm-egg interaction from the egg surface vitelline envelope (VE) and the paracrystalline protein fraction (PCF), derived from cortical granules. Although mature FEs are physicochemically hardened postinsemination, a major protein fraction consisting of seven major polypeptides was extracted from Strongylocentrotus purpuratus FEs and the major, separated components were immunologically cross-reactive with the principal polypeptides in PCF and isolated cortical granules. Antibodies prepared against extracted, core FEs were immunologically crossreactive with isolated VEs, but not with PCF, suggesting that only VE components are covalently crosslinked. Based on protease inhibitor experiments, our model of FE development is that a benzamidine-sensitive, cortical granule protease cleaves a 200 kD VE polypeptide during initial envelope elevation to set up the morphological change in FE papillae which occurs later. Divalent cations precipitate the PCF and form metal proteinate bridges between the VE and PCF. Based on peroxidase inhibitor experiments, we suggest that the cortical granule peroxidase crosslinks VE polypeptides, beginning at 2-3 min postinsemination, to restrict the permeability of the VE so that normal envelope thickening occurs. A 305 kD VE polypeptide was isolated and appears to be important in sperm-egg interaction based on inhibition of sperm binding and fertilization by antibodies against the purified polypeptide.
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Kessel RG. Annulate lamellae (porous cytomembranes): with particular emphasis on their possible role in differentiation of the female gamete. DEVELOPMENTAL BIOLOGY (NEW YORK, N.Y. : 1985) 1985; 1:179-233. [PMID: 3917201 DOI: 10.1007/978-1-4615-6814-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- R G Kessel
- Department of Biology, University of Iowa, Iowa City 52242
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17
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Dufresne-Dube L, Picheral B, Guerrier P. An ultrastructural analysis of Dentalium vulgare (Mollusca, Scaphopoda) gametes with special reference to early events at fertilization. JOURNAL OF ULTRASTRUCTURE RESEARCH 1983; 83:242-57. [PMID: 6876249 DOI: 10.1016/s0022-5320(83)90132-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The ultrastructure of Dentalium gametes, and their fate at fertilization, were investigated. Unexpectedly, fixation carried out in 2% osmium tetroxide, at 4 degrees C, although destroying most cytoplasmic organelles, reveals the presence of bundles of "stress fibers" in the microvilli and the fertilization cone of the eggs. Anti-actin labeling supports the view that the bundles are made of actin. Fertilization, as in other molluscs, does not cause any cortical granule exocytosis, at least during the first 15 min following insemination. Ultrastructure of the unreacted and reacted spermatozoon is presented and a tentative model for the morphological interpretation of the acrosomal reaction is proposed. A reevaluation of cytoplasmic heterogeneity, e.g., the so-called cytoplasmic prelocalization, as observed after the germinal vesicle breakdown is also provided as well as an analysis of concomitant surface changes.
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Kessel RG. The structure and function of annulate lamellae: porous cytoplasmic and intranuclear membranes. INTERNATIONAL REVIEW OF CYTOLOGY 1983; 82:181-303. [PMID: 6352549 DOI: 10.1016/s0074-7696(08)60826-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Carroll EJ, Endress AG. Sea urchin fertilization envelope: uncoupling of cortical granule exocytosis from envelope assembly and isolation of an envelope intermediate from Strongylocentrotus purpuratus embryos. Dev Biol 1982; 94:252-8. [PMID: 7152106 DOI: 10.1016/0012-1606(82)90089-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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GARWOOD PR. OBSERVATIONS ON THE CYTOLOGY OF THE DEVELOPING FEMALE GERM CELL IN THE POLYCHAETEHARMOTHOE IMBRICATA(L.). ACTA ACUST UNITED AC 1981. [DOI: 10.1080/01651269.1981.10553408] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Holland ND, Nealson KH. The Fine Structure of the Echinoderm Cuticle and the Subcuticular Bacteria of Echinoderms. ACTA ZOOL-STOCKHOLM 1978. [DOI: 10.1111/j.1463-6395.1978.tb01032.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kelsoe GH, Ubelaker JE, Allison VF. The fine structure of spermatogenesis in Hymenolepis diminuta (Cestoda) with a description of the mature spermatozoon. ZEITSCHRIFT FUR PARASITENKUNDE (BERLIN, GERMANY) 1977; 54:175-87. [PMID: 605649 DOI: 10.1007/bf00380800] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The processes of spermatogenesis and spermiogenesis in Hymenolepis diminuta were studied by electron microscopy using improved preparative techniques. Spermatogonia (Type A) are characterized by nuclei 3.79 (+/- 0.17) micrometer in diameter, dense cytoplasm packed with free ribosomes and aggregates of mitochondria. After mitoses, certain spermatogonia (Type B) assume syncytial rosettes containing eight nuclei. Primary spermatocytes maintain the rosette syncytium and have large nuclei (4.28 +/- 0.24 micrometer in diameter), smooth endoplasmic reticulum, and polysomes. The secondary spermatocyte is short-lived and is characterized by nuclei (2.0 +/- 0.11 micrometer in diai (2.0 +/- 0.11 micrometer in diameter) and perinuclear membranous lamellae. The syncytial spermatid cluster contains avoid nuclei which condense and elongate to a final diameter of 0.22 +/- 0.04 micrometer. Once elongated, these nuclei become delimited from the syncytium by invaginations of the plasma membrane. During delimitation, cortical peripheral microtubules arise beneath the spermatozoon plasmalemma and a 9 + 1 axoneme extends the length of the mature lance-shaped spermatozoon.
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Hylander BL, Summers RG. An ultrastructural analysis of the gametes and early fertilization in two bivalve molluscs, Chama macerophylla and Spisula solidissima with special reference to gamete binding. Cell Tissue Res 1977; 182:469-89. [PMID: 922818 DOI: 10.1007/bf00219830] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
An ultrastructural investigation of the gametes and their interaction during the early events of fertilization in molluscs has been performed. A gamete binding event involving large numbers of sperm has been identified and examined in detail. The surface of the oocyte is projected into numerous microvilli which extend through the vitelline envelope. Tufts of fibrillar material radiate from the tips of these microvilli, forming a layer external to the vitelline envelope. The acrosomal vesicle of the mature spermatozoon contains two major components, which function differently during fertilization. The vesicle is indented at its adnuclear surface, constituting a preformed acrosomal tubule. This tubule does not elongate during the acrosome reaction. Completion of the reaction results in the formation of an extracellular coat, derived from on component of the acrosomal vesicle, on the anterior surface of the sperm. Sperm-egg binding is accomplished by an association of the extracellular coat on the reacted sperm and the fibrous tufts on the tips of the microvilli of the oocyte. Evidence that gamete membrane fusion occurs by fusion of the acrosomal tubule and a microcillus is presented. These observations provide a generalized pattern of molluscan fertilization.
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Carroll EJ, Byrd EW, Epel D. A novel procedure for obtaining denuded sea urchin eggs and observations on the role of the vitelline layer in sperm reception and egg activation. Exp Cell Res 1977; 108:365-74. [PMID: 560975 DOI: 10.1016/s0014-4827(77)80043-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Gould-Somero M, Holland L, Paul M. Cytochalasin B inhibits sperm penetration into eggs of Urechis caupo (Echiura). Dev Biol 1977; 58:11-22. [PMID: 559601 DOI: 10.1016/0012-1606(77)90071-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Paul M, Johnson JD, Epel D. Fertilization acid of sea urchin eggs is not a consequence of cortical granule exocytosis. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1976; 197:127-33. [PMID: 939957 DOI: 10.1002/jez.1401970115] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Sea urchin eggs treated with 10 mM NHC1 release a "fertilization acid" although cortical granule exocytosis does not take place. If the eggs are inseminated following ammonia activation, the cortical reaction occurs and a fertilization membrane elevates in the absence of detectable acid release. Examination by electron microscopy of eggs fixed between ammonia activation and insemination confirms the presence of intact granules. Thus, the fertilization acid is not caused by the release of the cortical granules. Ammonia treatment of fertilized eggs stimulates further release of acid. The release of acid can occur repeatedly in ammonia activated eggs if they are washed into normal seawater between successive ammonia treatments. Our results suggest that the release of fertilization acid is related to some metabolic process which can be turned "on or off".
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Paul M, Gould-Somero M. Evidence for a polyspermy block at the level of sperm-egg plasma membrane fusion in Urechis caupo. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1976; 196:105-12. [PMID: 945322 DOI: 10.1002/jez.1401960110] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The results of sperm binding experiments reveal no change in the sperm binding properties of the egg surface coat at fertilization of Urechis caupo eggs. When fertilized eggs are reinseminated, sperm continue to attach to the egg surface coat. The acrosomal tubules of supernumerary sperm are observed in the perivitelline space closely apposed to the egg membrane. Thus, the polyspermy block in Urechis eggs involves neither alteration of sperm binding sites nor inhibition of the acrosome reaction. Our results suggest that the block is at the level of sperm-egg membrane fusion.
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Holland ND. The fine structure of the embryo during the gastrula stage of Comanthus japonica (Echinodermata: Crinoidea). Tissue Cell 1976; 8:491-510. [PMID: 982423 DOI: 10.1016/0040-8166(76)90009-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The fine structure of the embryo of Comanthus has been described by scanning and transmission electron microscopy at two-hourly intervals throughout the gastrula stage (from the fifth through the fifteenth hours of development). At 5 hr, gastrulation has occurred in the absence of any structure comparable to the echinoid hyaline layer; therefore, at least one important mechanism proposed for echinoid gastrulation cannot occur in this crinoid. At 7 hr, the blastocoelic basal lamina has formed, and all ectodermal and entodermal nuclei contain dense aggregates, which are probably perichromatin fibrils. At 9 hr, the blastocoel contains mesenchyme cells, presumably of entodermal origin. At 11 hr, ciliogenesis has started at the apical surfaces of the ectoderm cells and at the archenteral surfaces of the entoderm cells; many of the newly formed cilia are swollen subterminally. At 13 hr, a conspicuous glycocalyx is beginning to cover the apical ends of the ectoderm cells, and the fertilization membrane is beginning to dissolve from its inner surface. Between 5 and 13 hr, there is a gradual development of a junctional complex associating the apicolateral margins of the ectoderm cells; the zonula adherens part of the complex appears at 5 hr and is well developed by 7 hr, and then the septate junction part of the complex appears at 9 hr and is well developed by 13 hr. At 15 hr, the blastopore has closed, the ectodermal glycocalyx is fully developed, some mesenchyme cells appear to be differentiating into skeleton forming cells, and the fertilization membrane is in the last stages of dissolution.
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Gould-Somero M, Holland L. Fine structural investigation of the insemination response in Urechis caupo. Dev Biol 1975; 46:358-69. [PMID: 1242380 DOI: 10.1016/0012-1606(75)90112-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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