An overlooked placode: Recharacterizing the papillae in the embryonic eye of reptilia.

Autor: Drake PM; Department of Medical Neuroscience, Dalhousie University Faculty of Medicine, Halifax, Nova Scotia, Canada., Jourdeuil K; Department of Animal and Avian Sciences, University of Maryland at College Park, College Park, Maryland., Franz-Odendaal TA; Department of Biology, Mount Saint Vincent University, Nova Scotia, Canada.
Jazyk: angličtina
Zdroj: Developmental dynamics : an official publication of the American Association of Anatomists [Dev Dyn] 2020 Feb; Vol. 249 (2), pp. 164-172. Date of Electronic Publication: 2019 Nov 22.
DOI: 10.1002/dvdy.128
Abstrakt: The papillae in the chicken embryonic eye, described as scleral papillae in the well-known Hamburger and Hamilton (1951) staging table, are one of the key anatomical features used to stage reptilian (including bird) embryos from HH30-36. These papillae are epithelial thickenings of the conjunctiva and are situated above the mesenchymal sclera. Here, we present evidence that the conjunctival papillae, which are required for the induction and patterning of the underlying scleral ossicles, require epithelial pre-patterning and have a placodal stage similar to other placode systems. We also suggest modifications to the Hamburger Hamilton staging criteria that incorporate this change in terminology (from "scleral" to "conjunctival" papillae) and provide a more detailed description of this anatomical feature that includes its placode stage. This enables a more complete and accurate description of chick embryo staging. The acknowledgment of a placode phase, which shares molecular and morphological features with other cutaneous placodes, will direct future research into the early inductive events leading to scleral ossicle formation.
(© 2019 Wiley Periodicals, Inc.)
Databáze: MEDLINE
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