Rhythmic contractions in chick amnio-yolk sac and snake amnion during embryogenesis

Nechaeva, M. V.; Turpaev, T. M.

doi:10.1016/s1095-6433(02)00024-7

Cited by 18 publications

(8 citation statements)

References 13 publications

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“…The constricting force is achieved by the continuous contraction and tightening of the amniotic sleeve surrounding the yolk sac. The rhythmic contractions described in the amnion and yolk sac membrane of the chick (Nechaeva and Turpaev ) also raise the possibility that dual contractions of the two membranes may operate in tandem to facilitate the passage of the yolk sac through the amniotic sleeve. As internalization proceeds, the amniotic sleeve contracts and becomes smaller in size but greater in thickness, which likely results in the application of a greater force per unit area, thus countering the increasing resistance from the internalized portion of the yolk sac.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…The smooth muscle cells in the amnion are not innervated and contract spontaneously as well as in response to environmental stimuli (Turpaev and Nechaeva ; Nechaeva et al , , ; Nechaeva ). Amniotic motor activity does not occur in mammals and its role in birds and non‐avian reptiles is still unclear (Nechaeva and Turpaev ). The entire yolk deposit is engulfed by the highly vascularized yolk sac membrane and the metabolic products are transported to the embryo via the umbilical vitelline blood vessels (Thompson and Speake ).…”

Section: Introductionmentioning

confidence: 99%

“…Amniotic motor activity does not occur in mammals and its role in birds and non-avian reptiles is still unclear (Nechaeva and Turpaev 2002). The entire yolk deposit is engulfed by the highly vascularized yolk sac membrane and the metabolic products are transported to the embryo via the umbilical vitelline blood vessels (Thompson and Speake 2003).…”

Section: Introductionmentioning

confidence: 99%

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Hatching and residual yolk internalization in lizards: evolution, function and fate of the amnion

Pezaro

Doody

Green

et al. 2013

Evolution and Development

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Most egg-laying vertebrates hatch without depleting the entire yolk reserve. The residual yolk is internalized before emergence from the egg is completed and the yolk is subsequently metabolized during early neonatal life. Here we provide the first description of the mechanism of yolk internalization in non-avian reptiles. We describe the hatching of two lizard species (Physignathus lesueurii and Varanus rosenbergii) and provide a step-by-step account of sequence of events leading to yolk internalization and emergence from the egg. We also conducted incubation experiments to determine the cause of failed yolk internalization. Contraction of the ruptured amnion is the mechanism by which the residual yolk is internalized, which provides an explanation for the functional significance of amniotic contractions. Failures of internalization occur when the amount of residual yolk exceeds that which can be enclosed by the ruptured amnion. We conclude that, because of the connections formed between the amnion and both the allantois and chorion, the pipping and retraction of the amnion pulls the chorioallantoic membrane (CAM) off the surface of the eggshell, which impairs the capacity for gas exchange and forces the embryo to breach the eggshell to commence breathing. We further speculate that the loss of amniotic contractions in mammals may indicate an incompatibility of amnion-assisted yolk internalization with viviparity, an evolutionary process that could be tested by examining viviparous squamates.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hatching and residual yolk internalization in lizards: evolution, function and fate of the amnion

Pezaro

Doody

Green

et al. 2013

Evolution and Development

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“…The vasculature remains roughly in the same plane and bulk displacement is therefore small. Beyond 13 days, we observed slow chronic contractions of the CAM probably related to smooth muscle cells around arterioles, or to the contractility of extraembryonic organs 5,32,33 . This contraction causes arteries to stretch while veins become varicose.…”

Section: Introductionmentioning

confidence: 83%

Direct imaging of capillaries reveals the mechanism of arteriovenous interlacing in the chick chorioallantoic membrane

et al. 2018

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Understanding vascular development in vertebrates is an important scientific endeavor. Normal vasculatures generally start off as a disorganized capillary lattice which progressively matures into a well-organized vascular loop comprising a hierarchy of arteries and veins. One striking feature of vascular development is the interlacing of arteries and veins. How arteries and veins manage to avoid themselves and interlace with such a perfect architecture is not understood. Here we present a detailed view of the development of the vasculature in the chorioallantoic membrane of the chicken embryo. We find that the origin of arteriovenous interlacing lies in the presence of an increased hemodynamic resistance at the distal part of the arteries due to vascular flattening onto the ectodermal surface. This reduces the vascular conductance distally, thus repelling veins away. In more proximal parts, vessels round off into cylinders and the increased flow attracts veins.

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Turing conditions for pattern forming systems on evolving manifolds

2021

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Rhythmic contractions in chick amnio-yolk sac and snake amnion during embryogenesis

Cited by 18 publications

References 13 publications

Hatching and residual yolk internalization in lizards: evolution, function and fate of the amnion

Hatching and residual yolk internalization in lizards: evolution, function and fate of the amnion

Direct imaging of capillaries reveals the mechanism of arteriovenous interlacing in the chick chorioallantoic membrane

Turing conditions for pattern forming systems on evolving manifolds

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