The placenta and cardiac foramen ovale of the babirusa (Babyrousa babyrussa).

The structures of the placenta and the cardiac foramen ovale of the babirusa (Babyrousa babyrussa) were studied by means of light and scanning electron microscopy, with material from eleven fetal and neonatal animals. The babirusa has a diffuse epitheliochorial placenta. The chorion of the term placenta is fusiform in shape, and most of its surface comprises rows of villi interrupted by round, oval or irregularly shaped aerolae. A network of fetal placental capillaries indents the epithelial layer covering the tops and sides of the interareolar villi. The round and oval areolae have slender, irregularly shaped villi. The irregular areolae have undulating surfaces without villi. The umbilical cord contains two arteries, one vein and the urachus. The foramen ovale, when viewed from the terminal part of the caudal vena cava has the appearance of a tunnel; a fold of tissue projects from the caudal edge of the foramen ovale into the lumen of the left atrium. This fold, the distal end of which is straight-edged, constitutes a large proportion of the tube, the remainder being formed by the atrial septum. Comparison of the anatomy of the placenta and heart with those of members of the Suidae and Hippopotamidae indicates that the babirusa has more characters in common with the pigs than with the hippos.