How do Crocodylian embryos process yolk? Morphological evidence from the American alligator, Alligator mississippiensis.

Autor: Blackburn DG; Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA., Barnes MS; Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA., Reimers CD; Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA., Appiah FA; Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA., Lestz LL; Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA., Bonneau LJ; Department of Biology, and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA., Hanson M; Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA., Smith-Paredes D; Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA., Bhullar BA; Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA.
Jazyk: angličtina
Zdroj: Journal of morphology [J Morphol] 2021 Jul; Vol. 282 (7), pp. 953-958. Date of Electronic Publication: 2020 Aug 25.
DOI: 10.1002/jmor.21252
Abstrakt: Recent studies have demonstrated a mechanism of embryonic yolk processing in lizards, snakes and turtles that differs markedly from that of birds. In the avian pattern, cells that line the inside of the yolk sac take up products of yolk digestion and deliver nutrients into the vitelline circulation. In contrast, in squamates and turtles, proliferating endodermal cells invade and fill the yolk sac cavity, forming elongated strands of yolk-filled cells that surround small blood vessels. This arrangement provides a means by which yolk material becomes cellularized, digested, and transported for embryonic use. Ultrastructural observations on late-stage Alligator mississippiensis eggs reveal elongated, vascular strands of endodermal cells within the yolk sac cavity. The strands of cells are intermixed with free yolk spheres and clumps of yolk-filled endodermal cells, features that reflect early phases in the yolk-processing pattern. These observations indicate that yolk processing in Alligator is more like the pattern of other reptiles than that of birds.
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Databáze: MEDLINE
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