Evolución embriológica del órgano lingual del pollo

Abstract

Evolutionary. structural. ultrastructural anó cytochemical studies (PAS. alelan blue, toluidine blue. Ruthenium red] were performed in chick tongues 7to 19 days development. with the aim of observing the histomorphological changas during growth and difFerentiation. At 7 day; the tengue was covered by a Flat epithelium without cornification. With Four cell lines. As an axis was observad a central hyaline-cartilaginous skeleton surrounded by mesenchyma. Since 11 days appeared gland~ lar buds and canalizad cell cords united trough complexas. At 15 day; the epitelial thickness increased remarkably, The subepitelial connective tissue, already notably diFferentiated, formed papillae. Glandular acini contained PAS positiva. alcianophilic. metachromatic and positive ruthenium red substance. Ultrastructurally. glands showed clea-;:cells. with decreased electronic density and organoids randomly distri butedand dark cells having electrodense cytoplasm and more organizad oL: ganoids. At 19 days the epithelium was cornified in the tengue ante rior half,· A net increment oF glycoconjugates was detectad in glands These observations show: 1) lingual glands secrete mucíns since. 15 days of embryonic development;· 2) the cornified anterior epithelium is the result of a genetic pattern and not oF a later functional adapttion to the type oF feeding (grain eating birds].