Morphological characteristics of the placenta of Balami and Yankasa ewes at different stages of gestation in Maiduguri, Nigeria

The morphological characteristics of the placenta of Yankasa and Balami ewes were evaluated. Uteri of 20 pregnant Yankasa and Balami ewes were collected as abattoir waste from Maiduguri Municipal abattoir and were placed in containers containing 10% neutral buffered formalin. Using the crown-rump length (CRL) method of estimating the ages of the foetuses, they were grouped into three gestational stages. In both breeds, 50% of pregnancy occurred in the left uterine horn; in the Yankasa, 20% and 30% occur in the right uterine horn, and both (twining), respectively. While in the Balami, 40% and 10% occurred in the right and both (twinning) uterine horns, respectively. The results showed that the placenta-maternal contact in both breeds was fragile in the first stage, firm in the second stage, and loose in the third stage. The results showed that there were significant changes (P<0.001) in the mean weight, length, and width of the placentomes in all three stages. Three types of placenta appearances were identified in the Yankasa ewe: concave, convex, and flat, while two types of appearances in the Balami ewe were concave and convex. In the light microscopy evaluation, the trophoblastic epithelia of both ewes were composed of mononucleated, binucleated cells and syncytia. Endometrial glands were also observed in the inter-placental space. In conclusion, this study has shown that in both breeds, the cotyledonary surfaces of the placentae were mostly concave, followed by convex, and a mixture of the two (concave/convex). The trophoblast epithelia are positioned to control the movement of substances across foetal and maternal tissues. Even though little is still known about the regulation of these cells in the trophoblast epithelia, they are believed to be responsible for the synthesis of hormones such as lactogen for the maintenance of the pregnancy before parturition.