Premium
Deficits in the posterior pharyngeal endoderm in the absence of retinoids
Author(s) -
Quinlan Robyn,
Gale Emily,
Maden Malcolm,
Graham Anthony
Publication year - 2002
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.10137
Subject(s) - endoderm , pharyngeal pouch , biology , quail , pouch , retinoic acid , anatomy , retinoid , embryogenesis , embryo , microbiology and biotechnology , embryonic stem cell , endocrinology , genetics , gene
Recent studies have shown that the pharyngeal endoderm plays a critically important role in directing the development of the pharyngeal region of the vertebrate embryo. We have, however, had few insights into how the pharyngeal endoderm itself is patterned. Recently, several studies have suggested that retinoic acid is required for the development of the pharyngeal endoderm. To study this proposal in greater depth, we have examined the development of the pharyngeal endoderm in the absence of retinoid signalling, by using the vitamin A– deficient (VAD) quail model system. We find in early stages that, in the absence of retinoids, this territory extends further caudally than normal. Furthermore, as development proceeds, we find that the first pouch invariably forms, that the second pouch is abnormal, and that the third and fourth pharyngeal pouches never form. We do find, however, that dorsoventral patterning of the pharyngeal endoderm is unaffected. Finally, we have examined the expression patterns of RALDH2 before and during early development of the pharyngeal pouches. We find that this enzyme is expressed adjacent to the pharyngeal endoderm in tissues around the regressing anterior intestinal portal and that from stage 12 onward its anterior limit of expression lies at the level of the second pouch. This finding helps explain why the first pouch always forms in the absence of retinoids, and why defects are seen starting with the second and most evidently in the caudal pouches. © 2002 Wiley‐Liss, Inc.