Avaliação histológica do tegumento de fetos anelorados durante o período intrauterino como ferramenta morfológica para diagnóstico da idade fetal

Abstract

This study aims to evaluate the development of the integument of Zebu cattle fetuses and validate the methodology as a tool to determine fetal age. Samples were collected of the lateral face of the left hind limb of 24 fetuses, in a refrigerator. It was estimated fetal age by the length neck-tail in the formula GD = 8.4 +0, +5.46 √ c 087c (DG = day of gestation, c = length neck-tail). The fetuses were divided into three stages of gestation. The fragments were embedded in paraffin, stained with hematoxylin-eosin and evaluated by light microscopy. In the first trimester the epidermis showed a basal ovoid cells and flattened superficial cells, and the dermis, a loose connective tissue with thin collagen fibers, vessels and nerves. There were no skin appendages. In the epidermis of the second and third quarters were observed four distinct layers: a single row of basal cells, globose cells in the thorny, flattened cells in the granulosa and the cornea. The loose connective tissue of the dermis in the second quarter showed nerves and very vascularized. In the third quarter were observed hair follicles, sebaceous glands, apocrine sweat and a beam of the erector muscle of the hair. The absence of skin appendages indicates the first trimester of gestation. The beginning of the formation of hair follicles and glands characterizes the skin of fetuses between three and six months of gestation. If there is more differentiation of epidermal structures and the erector muscle of the hair, the fetus is close to birth. The microscopic examination of fetal integument can be used as a tool in determining the age of bovine Zebu fetuses.