Morphology of peri-partal placentomes and post-partal foetal membranes in African buffalo (Syncerus caffer) and comparative aspects with cattle (Bos taurus)

Field: Veterinary (Health Sciences)

The aim of this study was to describe the histo-morphology of the full-term placenta of African buffalo and to compare placental morphology between African buffalo and cattle. African buffalo, water buffalo and cattle differ, besides numerous external features, in various reproductive parameters such as gestational length. Interest in reproduction in African buffalo, including the application of assisted reproductive technologies, has gained momentum in recent years, with the aim of finding an efficient way of a) increasing genetic diversity and b) producing “disease free” offspring of this wild ruminant species. In contrast to the many studies on placentation in domesticated bovids (cattle and water buffalo), the placenta of African buffalo has been almost completely neglected. A polycotyledonary, synepitheliochorial placenta, characterized by the development of numerous placentomes is generally described for members of the bovid family. Cattle placentomes are stalked, mushroom shaped and represent sites of anchorage and close contact between mother and foetus via interdigitation of foetal cotyledonary villi within corresponding caruncular crypts. Placentomes from 3 peri-partal, and foetal membranes from 7 post-partal African buffalo cows were collected and placentomal and cotyledonary samples prepared for light microscopy (LM), scanningand transmission Electron Microscopy (SEM, TEM). The morphology and villous-crypt architecture of buffalo placentomes as well as the histology and ultrastructure of their structural components were described. Complete foetal membranes were macroscopically examined and cotyledonary villi were studied by SEM. A comparison with cattle placentomes and foetal membranes was performed directly or via comparison with relevant descriptions available in the literature. Comparison between buffalo and cattle placentae revealed that distribution pattern and placentome size were similar in both genera but that buffalo displayed considerably more placentomes than cattle. Buffalo placentomes were, in contrast to those of cattle, non-stalked. Differences in foetal villousity included long, slender and moderately branched villi in buffalo compared to broad, conical and complexly branched villi in cattle. Comparable cell types were involved in the synepitheliochorial interhaemal placental barrier in both genera but histological evidence for the process of placental maturation seems to be less pronounced in the buffalo than in the cattle placenta. The simpler villi in the non-stalked placentomes of the African buffalo form less complex fetomaternal interdigitations, which is interpreted as providing a somewhat less efficient nutrient supply to the developing foetus. This might partly explain the longer gestation period in buffalo compared to cattle. The placenta of water buffalo also contains non-stalked placentomes, thus resembling the African buffalo placenta in this respect, indicating a closer phylogenetic relationship between the two buffalo genera than between buffalo and cattle. Results of this first study of placentomes and foetal membranes of African buffalo fills large gaps existing in ruminant placentation and may provide the basis for further research in buffalo reproduction. The similarity in placental morphology between the African buffalo and water buffalo may enhance future trials of intergeneric embryo transfer between the two buffalo genera.