Análise macroscópica dos anexos embrionários e fetais de equinos em até 107 dias de gestação

Abstract

The horse (Equus caballus, Linneaus 1758) is a large ungulate mammal of the Equidea family, one of the seven modern species of the Equus genus. Domesticated for thousands of years, it is an unparalleled animal, of unusual beauty, grace, sensitivity and athletic ability; a fascinating animal for study, as described by Evans et al. (nineteen ninety); Ginther (1992) and Dantzer et al. (1998). Because it is not a simple model, it offers a comprehensive range for research and challenges scientists. Equine placentation and its embryonic development are some of the issues to be explored. Thus, this study aimed to describe microscopically the embryonic attachments of the embryo / fetus of horses in the first four months of pregnancy. In order to carry out this research, 37 placentas of adult, mixed breed mares were collected and divided into groups at the different stages of development, following the methodology employed by EVANS SACK (1973), until 107 days of gestation, and were subsequently destined for the microscopy of light. The membrane fragments (corium, allantois, amnion and yolk sac) were fixed in 10% formalin 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). In the four groups, the amnion presented with a simple pavement epithelium and mesenchyme without any vascularization, only vascularization was evident when the amnion fused with the allantois, which is also a simple pavement epithelium. The corium presented villi with a low columnar epithelium and brushed edges, uni and binucleated cells, highly vascularized, and the size and quantity of villi differed from the groups. The yolk sac presented an epithelium whose cells were large and globular, resting on the mesenchyme, forming vascular islands full of hemangioblasts, being non-existent in animals from 47 to 107 days of gestation.