Development in frogs with large eggs and the origin of amniotes

Elinson, Richard P.; Beckham, Yvonne M.

doi:10.1078/0944-2006-00060

Cited by 48 publications

(52 citation statements)

References 99 publications

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“…Various scenarios have been proposed for the sequence of appearance of increased yolk, meroblastic cleavage, and extraembryonic membranes among early amniotes (Elinson, 1989;Packard and Seymour, 1997;Stewart, 1997;Arendt and Nubler-Jung, 1999;Elinson and Beckham, 2002), but there is unlikely to be a fossil trilaminar omphalopleure (ectoderm, mesoderm, and endoderm). Blood vessels organize within the mesoderm and hematopoietic sites contribute the first blood cells to the developing embryo.…”

Section: Yolk Sac Structure Of Amniotesmentioning

confidence: 99%

Amniote yolk sacs: diversity in reptiles and a hypothesis on their origin

Elinson¹,

Stewart²,

Bonneau³

et al. 2014

Int. J. Dev. Biol.

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Oviparous amniotes produce a large yolky egg that gives rise to a free-living hatchling. Structural characteristics and functional attributes of the egg are best known for birds, which have a large mass of fluid yolk surrounded by an extraembryonic yolk sac. Yolk nutrients are delivered to the embryo via the vascular yolk sac. This developmental pattern and nutrient transport mechanism is thought to be representative of all other lineages of amniotes. Recent discovery of a snake with cellularized yolk organized around a meshwork of blood vessels reveals an additional pattern for yolk mobilization, which may also occur in other squamate reptiles (lizards and snakes). This complex yolk sac raises interesting questions about developmental mechanisms and suggests a possible model for the transition between the egg of anamniotes and that of amniotes.

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Section: Yolk Sac Structure Of Amniotesmentioning

confidence: 99%

Amniote yolk sacs: diversity in reptiles and a hypothesis on their origin

Elinson¹,

Stewart²,

Bonneau³

et al. 2014

Int. J. Dev. Biol.

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“…These membranes are the chorion, amnion, allantois and yolk sac. One of the major differences between the eggs of extant amphibians and of birds, snakes and other oviparous amniotes is the large amount of yolk in the amniote egg [1,2]. This increased yolk allowed the amniote embryo to hatch as a free-living animal without an aquatic, feeding larva.…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, there is unlikely to be a fossil record of these changes to delicate embryonic tissues. Possible scenarios can be constructed by examining the physiological and morphological variation in embryos of extant animals [1,2].…”

Section: Introductionmentioning

confidence: 99%

The corn snake yolk sac becomes a solid tissue filled with blood vessels and yolk-rich endodermal cells

Elinson

Stewart

2014

Biol. Lett.

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The amniote egg was a key innovation in vertebrate evolution because it supports an independent existence in terrestrial environments. The egg is provisioned with yolk, and development depends on the yolk sac for the mobilization of nutrients. We have examined the yolk sac of the corn snake Pantherophis guttatus by the dissection of living eggs. In contrast to the familiar fluid-filled sac of birds, the corn snake yolk sac invades the yolk mass to become a solid tissue. There is extensive proliferation of yolk-filled endodermal cells, which associate with a meshwork of blood vessels. These novel attributes of the yolk sac of corn snakes compared with birds suggest new pathways for the evolution of the amniote egg.

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“…The major phylogenetic importance that this structure has perhaps lies in that during development it protectively surrounds the embryo and creates a fullfilled cavity in which the embryo develops [178]. Its acquisition, that is, the "amniotic egg" was one of the main causes that enabled amniotes to escape the bonds that confined their ancestors to aquatic environments [178,188]. If so, it could be proposed that there this is no better method to escape the sea than taking the sea with us, as an amniotic-mesothelial structure full of saline trophic fluid [188,189].…”

Section: Portal Hypertensive Ascites and The Amniotic Way Of Lifementioning

confidence: 99%

“…Its acquisition, that is, the "amniotic egg" was one of the main causes that enabled amniotes to escape the bonds that confined their ancestors to aquatic environments [178,188]. If so, it could be proposed that there this is no better method to escape the sea than taking the sea with us, as an amniotic-mesothelial structure full of saline trophic fluid [188,189]. Since this ability would be associated in the post-natal life with mesothelial cells, its major spread through the body is not surprising, coating cavities, i.e.…”

Section: Portal Hypertensive Ascites and The Amniotic Way Of Lifementioning

confidence: 99%

Portal hypertension-related inflammatory phenotypes: From a vitelline and amniotic point of view

Aller¹,

Arias²,

Prieto³

et al. 2012

ABB

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Prehepatic portal hypertension induces a splanchnic low-grade inflammatory response that could switch to high-grade inflammation with the development of severe and life-threatening complications when associated with chronic liver disease. The extraembryonic origin of the portal system maybe determines the regression to an extraembryonic phenotype, i.e., vitellogenic and amniotic, during the evolution of both types of portal hypertension. Thus, prehepatic portal hypertension, or compensated hypertension by portal vein ligation in the rat, is associated with molecular mechanisms related to vitellogenesis, where hepatic steatosis and splanchnic angiogenesis stand out. In turn, extrahepatic cholestasis in the rat induces intrahepatic portal hypertension, or decompensated hypertension, with ascites and hepatorenal syndrome. The splanchnic interstitium, the mesenteric lymphatic system, and the peritoneal mesothelium seem to create an inflammatory pathway that could have a key pathophysiological relevance in the production of ascites. The hypothetical comparison between the ascitic and the amniotic fluid also allows for translational investtigation. The induced regression of the splanchnic system to extraembryonic functions by portal hypertension highlights the great relevance of the extraembryonic structures even during post-natal life.

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Development in frogs with large eggs and the origin of amniotes

Cited by 48 publications

References 99 publications

Amniote yolk sacs: diversity in reptiles and a hypothesis on their origin

Amniote yolk sacs: diversity in reptiles and a hypothesis on their origin

The corn snake yolk sac becomes a solid tissue filled with blood vessels and yolk-rich endodermal cells

Portal hypertension-related inflammatory phenotypes: From a vitelline and amniotic point of view

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