Myrmecophaga tridactyla , term placentas. (A) Vimentin. Villi were strongly vimentin-positive, in contrast to the solid trophoblast of trabeculae (trab). (B) Masson’s trichrome. Branching villi (arrows) with fibers. Fetal capillaries (arrowheads) near the surface of the villi. (C) Vimentin-negative syncytial trophoblast (syn) and trophoblast cells (ct). Positive response in hypertrophied mesenchymal cells (mc) and capillary endothelium (arrow). No remnants of the maternal endothelium were present along the villi and trabeculae. (D) Cytokeratin-positive trophoblast of the trabeculae (arrow). (E) Vimentin. Trophoblast (ct) of trabeculae (vimentin negative) occasionally invaded decidua (vimentin-positive). (F) PCNA. Proliferation in trophoblast of villi and trabeculae (arrows).