part of part of in taxon contributes to morphology of Homo sapiens placenta placenta labyrinth http://placentation.ucsd.edu/placenta.html Mouse-human differences: The mouse and human placentas have labyrinthine and villous types of interdigitation between maternal and fetal tissues, respectively ... The mouse placental labyrinth is composed of an intricate network of maternal blood spaces and embryonal blood vessels. Maternal and embryonal blood is separated by a placental barrier that consists of four cellular layers: layer I trophoblasts line the maternal lacunae, trophoblasts in layers II and III form syncytial-like layers, and endothelial cells line the embryonic vessels[DOI: 10.1073/pnas.96.14.8138 ] labyrinthine layer placental labyrinth labyrinthine layer of placenta The placental layers where embryonic blood vessels are surrounded by trophoblast cells and maternal blood. UBERON:0003946 reproductive structure