Placentation in the Amazonian manatee (Trichechus inunguis)

• Autor(a) principal: Carter, Anthony M.
• Data de Publicação: 2008
• Outros Autores: Miglino, Maria Angelica, Ambrósio, Carlos Eduardo, dos Santos, Tatiana Carlesco, Weber Rosas, Fernando Cesar, D'Affonsêca Neto, José Anselmo, Lazzarini, Stella Maris, Carvalho, Ana Flávia de, Silva, Vera Maria Ferreira da
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional do INPA
• Texto Completo: https://repositorio.inpa.gov.br/handle/1/16342
• topic: Animals Cell; Animals Tissue; Blood Vessel; Cell Ultrastructure; Columnar Epithelium; Controlled Study; Cytotrophoblast; Female; Fetus Circulation; Fetus Membrane; Histopathology; Immunohistochemistry; Inner Ear; Nonhuman; Phylogeny; Placental Delivery; Reproduction; Microscopy, Electron, Scanning; Trichechus Inunguis; Trophoblast; Umbilical Cord; Vascularization; Afrotheria; Elephantidae; Sirenia; Trichechus Inunguis

Evidence from several sources supports a close phylogenetic relationship between elephants and sirenians. To explore whether this was reflected in similar placentation, we examined eight delivered placentae from the Amazonian manatee using light microscopy and immunohistochemistry. In addition, the fetal placental circulation was described by scanning electron microscopy of vessel casts. The manatee placenta was zonary and endotheliochorial, like that of the elephant. The interhaemal barrier comprised maternal endothelium, cytotrophoblasts and fetal endothelium. We found columnar trophoblast beneath the chorionic plate and lining lacunae in this region, but there was no trace in the term placenta of haemophagous activity. The gross anatomy of the cord and fetal membranes was consistent with previous descriptions and included a four-chambered allantoic sac, as also found in the elephant and other afrotherians. Connective tissue septae descended from the chorionic plate and carried blood vessels to the labyrinth, where they gave rise to a dense capillary network. This appeared to drain into shorter vessels near the chorionic plate. The maternal vasculature could not be examined in the same detail, but maternal capillaries ran rather straight and roughly parallel to the fetal ones. Overall, there is a close resemblance in placentation between the manatee and the elephant. © CSIRO 2008.