Abstract:During pregnancy the viviparous vertebrates develop a complex system of nutritional membranes surrounding the fetus. In place of the union or apposition of the fetal membranes with the uterine lining ...During pregnancy the viviparous vertebrates develop a complex system of nutritional membranes surrounding the fetus. In place of the union or apposition of the fetal membranes with the uterine lining is formed the placenta. The placental types may be categorized into several complementary levels that reflect placental characteristics, being the swine placenta classified as chorioallantoic, diffuse, pleated, epitheliochorial and cross to counter-current. Structures, as the yolk sac, have function even before the appearance of the chorioallantoic placenta. The areola is also an accessory structure of the placenta, which may be found in ungulates. The extraembryonic membranes are linked intimately in the placentation, and these are important in swine early pregnancy, since the definitive placenta starts developing by the 18th day of gestation. Modifications in the swine placenta, like the presence of areolas, might have arisen as domestic species adaptions in order to supply nourishing needs during the development of concept.Read More
Publication Year: 2015
Publication Date: 2015-12-31
Language: en
Type: article
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Cited By Count: 8
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