Placental arteries and veins in wooless mongrel sheep (Ovis aries, L. 1758)

Abstract

The blood supply of placenta of 30 wooless sheep without a defined breed was studied by analyzing the pieces obtained through vascular injection of Latex Neoprene 650 stain solution and moulds were made from injection of vinyl acetate. Single gestation (53.33%), gemel (46.66%) and trigeminal (3.33%) cases were observed; in all cases studied it was observed 4 umbilical vessels (2 arteries and 2 veins) besides the allantoidal duct forming the funiculus. Only in one case (trigeminal gestation), the two umbilical arteries of one of the fetuses were fused at he intermediary part of the umbilical funiculus. The hilar area of the placenta varied from 2.0 to 6.0 centimeters depending on the gestational phase. The mean number of cotyledons per gestation was 96 and their sizes and shapes were varied, being the most predominant those greater than 1.5 centimeter and also the ones with ovoid form. The cotyledons were irrigated and drained by a number of diversified arteries and veins, constituting arteriocotyledonary and venocotyledonary arrangements, numbering a total of 299 and 314 casting moulds, respectively.