THE PLACENTA AND CARDIAC FORAMEN OVALE OF THE BABIRUSA (BABYROUSA-BABYRUSSA)

The structures of the placenta and the cardiac foramen ovale of the ba birusa (Babyrousa babyrussa) were studied by means of light and scanni ng electron microscopy, with material from eleven fetal and neonatal a nimals. The babirusa has a diffuse epitheliochorial placenta. The chor ion of the term placenta is fusiform in shape, and most of its surface comprises rows of villi interrupted by round, oval or irregularly sha ped aerolae. A network of fetal placental capillaries indents the epit helial layer covering the tops and sides of the interareolar villi. Th e round and oval areolae have slender, irregularly shaped villi. The i rregular areolae have undulating surfaces without villi. The umbilical cord contains two arteries, one vein and the urachus. The foramen ova le, 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 edg e of the foramen ovale into the lumen of the left atrium. This fold, t he distal end of which is straight-edged, constitutes a large proporti on of the tube, the remainder being formed by the atrial septum. Compa rison of the anatomy of the placenta and heart with those of members o f the Suidae and Hippopotamidae indicates that the babirusa has more c haracters in common with the pigs than with the hippos.