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Bi‐modal strategy of gastrulation in reptiles
Author(s) -
Stower Matthew J.,
Diaz Raul E.,
Fernandez Lucia Carrera,
Crother Mary White,
Crother Brian,
Marco Adolfo,
Trainor Paul A.,
Srinivas Shankar,
Bertocchini Federica
Publication year - 2015
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/dvdy.24300
Subject(s) - gastrulation , ingression , biology , primitive streak , amniote , brachyury , anatomy , epiblast , microbiology and biotechnology , embryo , mesoderm , embryogenesis , vertebrate , embryonic stem cell , genetics , gene
Background: Amniote gastrulation is often described with respect to human, mouse and chick development by the presence of the primitive streak, a posterior‐to‐anterior midline morphological cell ingression feature that has come to define Amniote gastrulation. How this midline, ingression‐based strategy of gastrulation evolved from the ancestral blastopore, a circumferential involution event in Anamniotes, is unknown. However, within the Amniote clade there exists a more diverse range of gastrulation strategies than just the primitive streak. Investigating gastrulation in a wider range of Amniotes provides a way to understand evolutionary transition from blastopore to the primitive streak. Results: We analysed early to late gastrulation stages of Chamaeleo calyptratus , showing their unique morphology through confocal imaging of F‐actin and laminin‐stained embryos to visualise cell morphology and assess basal lamina integrity. We analysed the expression pattern of core mesodermal markers Brachyury and Fgf8 and complimented this analysis with that of the turtle, Trachemys scripta . Conclusions: Our analysis suggests that reptile gastrulation is bi‐modal; primary internalization occurs anteriorly by means of an incomplete blastopore‐like opening, while posteriorly the cells undergo ingression in the Brachyury‐ expressing blastoporal plate. This strategy stands mid‐way between Anamniotes and Avians/Mammals, suggesting that blastoporal plate is a precursor of the avian primitive streak. Developmental Dynamics 244:1144–1157, 2015 . © 2015 Wiley Periodicals, Inc.