Myrmecophaga tridactyla , mid gestation placenta. (A,B) Macroscopic anatomy. Uterus (U) with lobulated structure, an extended chorioallantoic placenta (CP), areas of gelatinous appearance (arrows), and a single embryo (E). (C) Haematoxylin and eosin. One umbilical vein (uv) and two arteries (ua) entered the placenta from the chorionic plate (chor plat). (D) Haematoxylin and eosin. Intermingling of villous (villi) and trabeculae (trab) areas, bathed in maternal blood (arrows). (E) Haematoxylin and eosin. Both villi and trabeculae reached the decidua (dec). (F) Cytokeratin-positive trophoblast of trabeculae (arrows) attached to the decidua that was cytokeratin-negative.