Análise microscópica e ultraestrutura do saco vitelino de equinos com até 47 dias de gestação

Abstract

This work aimed to describe microscopically the yolk sac of horses up to 47 days of gestation. To carry out this research, 37 placentas and embryos from 15 to 47 days of gestation were collected. The material was taken from adult, mixed breed mares in a slaughterhouse. Embryonic age was estimated according to the methodology used by EVANS SACK (1973). The embryos were destined for microscopic analysis. For analysis under light microscopy the fragments of the yolk sac membranes were fixed in 10% formaldehyde and Bouin followed by routine paraffin processing (TOLOSA et al; 2003). Serial slices with a thickness of 5μm were obtained in a microtome (Leica 2165®) which were submitted to staining by the methods of hematoxylin and eosin, picrosirius, Toluidine blue and Masson's trichrome (TOLOSA et al; 2003). Another part of the material was submitted to transmission and scanning electron microscopy. The yolk sac epithelium varied from globular to columnar, with uni or binucleated cells in a single layer, with a large amount of rough endoplasmic reticulum, distributed evenly, the epithelium supported on the mesenchyme forming vascular islands filled with hemangioblasts, being non-existent in animals older than 47 days of gestation; and characteristics of protein secretion.