Tamandua tetradactyla , late gestation or near term placenta. (A) Macroscopic anatomy. Placenta disc (CP) with branching umbilical vessels (arrows) along an area of gelatinous tissue (gel) and a single fetus (F). (B) α-smooth muscle actin. Villi in the intervillous space (ivs) with immuno-positive fetal capillary endothelium (end) and hypertrophied mesenchymal cells (mc). No remnants of maternal endothelium were present. (C) Cytokeratin. Trophoblast cells of the trabeculae (trab) were positive (arrows), facing towards the intervillous space. (D) Haematoxylin and eosin. Trophoblast of the trabeculae (arrow) attached to the connective tissue and musculature of the uterus (ut).