Classification of human placental villi. II. Morphometry.

Villi of placental tissue obtained from normal term placentae at Caesarean section were embedded in Epon. Semithin sections were subjected to morphometry. The villi were first grouped according to the modified classification proposed in the foregoing paper. The parameters examined include villous numbers, size, vascularity, volume of trophoblast and connective tissue. The measured values differ markedly from those obtained from paraffin sections. Statistically significant differences exist between the different types of villi in various parameters, providing further evidence supporting the validity of the structural classification suggested.