Histological characterization of the utero-placental membranes of alpaca
The biology of the alpaca placenta shows the interaction of maternal-embryonic-fetal structures, which are responsible for maintaining the stability and viability of the new being, from its conception to birth. It is a biological system that obeys hormonal and molecular changes whose expression is visualized in the morphodynamics of the elements that compose it. The alpaca placenta must develop a high capacity to transport nutrients from the maternal to the fetal side and metabolites from the fetal to the maternal side. The implantation process is a state of transition in the progress of the pregnancy, during which the blastocyst assumes a fixed position and initiates a physiological interrelation with the uterus. To guarantee this process, the presence of the corpus luteum is necessary for camelids. The uterine surface shows spherical depressions in different degrees of development where the projections of the trophoblast correspond. The uterine epithelium is presented in the form of a simple flat epithelium showing cellular synthesis activity and next to the maternal-fetal interface it exhibits conjunction of electrodense material made up of bundles of microfilaments. The maternal-fetal interface of positive reaction to alkaline phosphatase is evidenced by the interdigitation of microvilli of both tissues, maternal and fetal, the trophoblast being of greater dimensions, so interdigitation is incomplete. The passage of substances is evidenced in the walls of the maternal and fetal capillaries, this molecular exchange seems to be favored by the reduced distance between both capillaries due to the indentation of the fetal capillaries in the trophoblastic layer and the decrease in the thickness of the uterine epithelium and evident increase in the capillary subepithelial vascular network. The data shown in the characterization of the alpaca placenta suggest that despite being considered a diffuse, epitheliochorial placenta, it contains specialized regions functioning as histotrophic sites, increasing molecular exchange.