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Australian Journal of Biological... Jun 1969
Topics: Animals; Chick Embryo; Epithelial Cells; Female; Microscopy, Electron; Ovulation; Vitelline Membrane
PubMed: 5801278
DOI: 10.1071/bi9690653 -
Journal of Morphology Oct 2008Although the majority of onychophorans are viviparous or ovoviviparous, oviparity has been described in a number of species found exclusively in Australia and New...
Although the majority of onychophorans are viviparous or ovoviviparous, oviparity has been described in a number of species found exclusively in Australia and New Zealand. Light microscopy and scanning and transmission electron microscopy were used to examine developing eggs and the reproductive tract of the oviparous Planipapillus mundus. Deposited eggs and fully developed eggs dissected from the terminal end of the uteri have an outer thick, slightly opaque chorion, and an inner thin, transparent vitelline membrane. The chorion comprises an outermost extrachorion, sculptured with domes equally spaced over the surface; a middle exochorion, with pores occurring in a pattern of distribution equivalent to that of the domes of the extrachorion above; and an innermost, thick endochorion consisting of a spongelike reticulum of cavities comparable to the respiratory network found in insect eggs. The vitelline membrane lies beneath the chorion, from which it is separated by a fluid-filled space. The vitelline membrane tightly invests the developing egg. Examination of oocytes in the ovary and developing eggs at various stages of passage through the uterus indicate that the majority of chorion deposition occurs in the midregion of the uterus, where vast networks of endoplasmic reticulum are present in the columnar epithelium. The vitelline membrane, however, is believed to begin its development as a primary egg membrane, surrounding the developing oocytes in the ovary. The vitelline membrane is transformed after fertilization, presumably by secretions from the anterior region of the uterus; hence, it should be more accurately referred to as a fertilization membrane. Aspects of the reproductive biology of P. mundus are also included.
Topics: Animals; Egg Shell; Female; Invertebrates; Male; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Oocytes; Ovary; Vitelline Membrane
PubMed: 18677704
DOI: 10.1002/jmor.10658 -
Zeitschrift Fur Zellforschung Und... Jul 1971
Topics: Animals; Autoradiography; Biometry; Drosophila; Embryo, Nonmammalian; Endoplasmic Reticulum; Extraembryonic Membranes; Female; Inclusion Bodies; Lipids; Microscopy, Electron; Microtubules; Mitochondria; Ovary; Ovum; Proteins; Vitelline Membrane
PubMed: 4327628
DOI: 10.1007/BF00324615 -
Frontiers in Bioscience : a Journal and... May 2008The zona pellucida (ZP) is a unique extracellular coat surrounding the maturing oocyte, during ovulation, fertilization, and early embryo development. It is formed by... (Review)
Review
The zona pellucida (ZP) is a unique extracellular coat surrounding the maturing oocyte, during ovulation, fertilization, and early embryo development. It is formed by three/four glycoproteins. Ultrastructural data obtained with transmission (TEM) and scanning electron microscopy (SEM) were compared with molecular data on the glycoproteins network from ovulation to blastocyst formation. Molecular models are quite different to the morphology obtained with TEM, which shows a microfibrillar architecture, or with SEM, which shows a spongy or smooth surface. The saponin-ruthenium red-osmium tetroxide-thiocarbohydrazide technique allows to show the ZP real microfilamentous structure and the related functional changes. These results support an ultrastructural supramolecular model, more similar and comparable to molecular models related with the glycoprotein network. A detailed mapping of single mammalian ZP proteins and their relationship within the supramolecular architecture of the zona matrix would clearly supply insights into the molecular basis of sperm-egg recognition. Differences in ZP glycoproteins among mammals do not affect structural morphology; further studies are needed to clarify the relationships between ultrastructural and molecular organizations.
Topics: Animals; Embryonic Development; Female; Fertilization; Male; Mammals; Microscopy, Electron, Scanning; Oocytes; Ovulation; Sperm-Ovum Interactions; Vitelline Membrane; Zona Pellucida
PubMed: 18508691
DOI: 10.2741/3185 -
Developmental Biology (New York, N.Y. :... 1985As the material presented in this chapter was being collated, our existing perceptions about the basic similarities of vertebrate (and indeed most, if not all,... (Review)
Review
As the material presented in this chapter was being collated, our existing perceptions about the basic similarities of vertebrate (and indeed most, if not all, invertebrate) egg envelopes became increasingly strengthened. Perhaps without exception, all vertebrate and invertebrate eggs acquire a "vitelline" envelope. Interestingly, its filamentous ultrastructure and chemical composition--basically protein and carbohydrate--is similar in all species as is its permeability to large molecules. Furthermore, many (if not all) of its functions are shared among the animal phyla as is its potential to become altered at the time of fertilization and, in its altered state, to provide a new set of modi operandi. It provides sperm receptors that are generally species specific and helps prevent polyspermy; it protects the developing embryo yet yields at the time of hatching. In most vertebrate eggs (including some mammals), a jelly or albumen coat is added to the vitelline envelope. These components may vary immensely in thickness, but again their basic chemical composition is common to all. The functions of these envelopes, while perhaps somewhat less clear than those of the vitelline envelope, are related to species-specific fertilization and to embryonic protection. Albumen serves a nutritional role--most clearly shown in the birds. Finally, the shell membrane and shell present in diverse groups contribute additional adaptations for embryo protection. Vertebrate egg envelopes, then, are basically similar; the modifications, including the addition of shell membranes and shells in some groups, reflect adaptations to differing reproductive strategies and to the environmental exigencies with which the egg must cope. With the growth of our understanding about the structure, chemistry, function, and evolution of egg envelopes new questions will continually be formulated. Many will be the same as those asked years ago but they will be answered with newer techniques and with greater insight.
Topics: Animals; Ovum; Vertebrates; Vitelline Membrane
PubMed: 3917202
DOI: 10.1007/978-1-4615-6814-8_5 -
Journal of the Royal Society, Interface Nov 2016During early development, the tubular embryonic chick brain undergoes a combination of progressive ventral bending and rightward torsion, one of the earliest organ-level...
During early development, the tubular embryonic chick brain undergoes a combination of progressive ventral bending and rightward torsion, one of the earliest organ-level left-right asymmetry events in development. Existing evidence suggests that bending is caused by differential growth, but the mechanism for the predominantly rightward torsion of the embryonic brain tube remains poorly understood. Here, we show through a combination of experiments, a physical model of the embryonic morphology and mechanics analysis that the vitelline membrane (VM) exerts an external load on the brain that drives torsion. Our theoretical analysis showed that the force is of the order of 10 micronewtons. We also designed an experiment to use fluid surface tension to replace the mechanical role of the VM, and the estimated magnitude of the force owing to surface tension was shown to be consistent with the above theoretical analysis. We further discovered that the asymmetry of the looping heart determines the chirality of the twisted brain via physical mechanisms, demonstrating the mechanical transfer of left-right asymmetry between organs. Our experiments also implied that brain flexure is a necessary condition for torsion. Our work clarifies the mechanical origin of torsion and the development of left-right asymmetry in the early embryonic brain.
Topics: Animals; Brain; Chick Embryo; Chickens; Models, Biological; Organogenesis; Vitelline Membrane
PubMed: 28334695
DOI: 10.1098/rsif.2016.0395 -
The Journal of Physiology Feb 20001. Mechanical stimulation of voltage-clamped Xenopus oocytes by inflation, aspiration, or local indentation failed to activate an increase in membrane conductance up to...
1. Mechanical stimulation of voltage-clamped Xenopus oocytes by inflation, aspiration, or local indentation failed to activate an increase in membrane conductance up to the point of causing visible oocyte damage. 2. The absence of mechanosensitivity is not due to the vitelline membrane, rapid MG channel adaptation or tension-sensitive recruitment of new membrane. 3. Membrane capacitance measurements indicate that the oocyte surface area is at least 5 times larger than that predicted assuming a smooth sphere. We propose that this excess membrane area provides an immediate reserve that can 'buffer' membrane tension changes and thus prevent MG channel activation. 4. High-resolution images of tightly sealed patches and patch capacitance measurements indicate a smooth membrane that is pulled flat and perpendicular across the inside of the pipette. Brief steps of pressure or suction cause rapid and reversible membrane flexing and MG channel activation. 5. We propose that changes in membrane geometry induced during cell growth and differentiation or as a consequence of specific physiological and pathological conditions may alter mechanosensitivity of a cell independently of the intrinsic properties of channel proteins.
Topics: Adaptation, Physiological; Animals; Cell Membrane; Electric Conductivity; Female; Insufflation; Ion Channel Gating; Mechanoreceptors; Oocytes; Patch-Clamp Techniques; Physical Stimulation; Suction; Vitelline Membrane; Xenopus laevis
PubMed: 10673547
DOI: 10.1111/j.1469-7793.2000.00101.x -
Nature Dec 1995
Topics: Animals; Female; Fishes; Male; Oocytes; Ovulation; Pheromones; Tetrodotoxin; Vitelline Membrane
PubMed: 8524387
DOI: 10.1038/378563b0 -
Zygote (Cambridge, England) May 2006During activation of amphibian eggs, cortical granule exocytosis causes elaborate ultrastructural changes in the vitelline envelope. These changes involve modifications...
During activation of amphibian eggs, cortical granule exocytosis causes elaborate ultrastructural changes in the vitelline envelope. These changes involve modifications in the structure of the vitelline envelope and formation of a fertilization envelope (FE) that can no longer be penetrated by sperm. In Bufo arenarum, as the egg traverses the oviduct, the vitelline envelope is altered by a trypsin-like protease secreted by the oviduct, which induces an increased susceptibility of the vitelline envelope to sperm lysins. Full-grown oocytes of B. arenarum, matured in vitro by progesterone, are polyspermic, although cortical granule exocytosis seems to occur within a normal chronological sequence. These oocytes can be fertilized with or without trypsin treatment, suggesting that the vitelline envelope is totally sperm-permeable. Vitelline envelopes without trypsin treatment cannot retain either gp90 or gp96. This suggests that these glycoproteins are involved in the block to polyspermy and that trypsin treatment of matured in vitro oocytes before insemination is necessary to enable vitelline envelopes to block polyspermy. The loss of the binding capacity in vitelline envelopes isolated from B. arenarum oocytes matured in vitro with trypsin treatment and activated by electric shock suggests that previous trypsin treatment is a necessary step for sperm block to occur. When in vitro matured oocytes were incubated with the product of cortical granules obtained from in vitro matured oocytes (vCGP), vitelline envelopes with trypsin treatment were able to block sperm entry. These oocytes exhibited the characteristic signs of activation. These results support the idea that B. arenarum oocytes can be activated by external stimuli and suggest the presence of unknown oocyte surface receptors linked to the activation machinery in response to fertilization. Electrophoretic profiles obtained by SDS-PAGE of solubilized vitelline envelopes from oocytes matured in vitro revealed the conversion of gp40 (in vitro matured oocytes, without trypsin treatment) to gp38 (ascribable to trypsin activity or cortical granule product activity, CGP) and the conversion of gp70 to gp68 (ascribable to trypsin activity plus CGP activity). Taking into account that only the vitelline envelopes of in vitro matured oocytes with trypsin treatment and activated can block sperm entry, we may suggest that the conversion of gp70 to gp68 is related to the changes associated with sperm binding.
Topics: Animals; Bufo arenarum; Female; Fertilization; Male; Oocytes; Sperm-Ovum Interactions; Spermatozoa; Vitelline Membrane
PubMed: 16719945
DOI: 10.1017/S0967199406003662 -
Biology of Reproduction Apr 2002Vitelline envelopes (VEs) of Bufo arenarum were isolated in order to study their composition and their role in fertilization. VEs are composed of four glycoproteins,...
Vitelline envelopes (VEs) of Bufo arenarum were isolated in order to study their composition and their role in fertilization. VEs are composed of four glycoproteins, with molecular masses of 120, 75, 41, and 38 kDa. To characterize its biological properties, we quantitatively determined sperm-VE binding and the induction of the acrosome reaction. Heterologous binding of B. arenarum sperm to Xenopus laevis VE components was observed with about one-third the efficiency of homologous binding. Equivalent binding of X. laevis sperm to the B. arenarum VE was observed. When B. arenarum sperm were incubated with fluorescein isothiocyanate-labeled VE, the labeled glycoproteins bound to the anterior end of the sperm head, showing a lateral distribution. Induction of the acrosome reaction was evaluated by incubating sperm in hypotonic saline media with VE glycoproteins. VEs induced the acrosome reaction in a time- and concentration-dependent manner. The acrosome reaction was maximal after 10 min. The half-maximal effect was obtained at a glycoprotein concentration of 1 microg/ml. Specificity was determined using fertilization envelope glycoproteins, which failed to induce the acrosome reaction. The B. arenarum VE is biochemically similar to other egg envelopes. It also seems that its biological properties are similar to other species in regard to sperm binding and induction of the acrosome reaction. However, as far as we are aware, this is the first observation of the VE inducing the sperm acrosome reaction in amphibians. The relatively small differences observed in heterologous sperm-VE binding in X. laevis and B. arenarum are inconsistent with the current paradigm that species specificity in fertilization is regulated at the sperm-VE binding step.
Topics: Acrosome Reaction; Animals; Bufo arenarum; Electrophoresis, Polyacrylamide Gel; Female; Fertilization; Fluorescein-5-isothiocyanate; Fluorescent Dyes; Glycoproteins; Male; Microscopy, Fluorescence; Molecular Weight; Spermatozoa; Vitelline Membrane
PubMed: 11906942
DOI: 10.1095/biolreprod66.4.1203