Stereological study of the effect of altitude on the trophoblast cell populations of human term placental villi

Paraffin-embedded histological material was examined from 10 placentae from uncomplicated pregnancies at high altitude (3000 m). This was compared with material from 10 placentae delivered at low altitude (500 m). The sample groups were matched for maternal age, gestational age and parity. Within terminal and intermediate villi the volume-weighted mean cytotrophoblast cell volume did not significantly change at high altitude (754.1 μm 3 at low altitude versus 796 μm 3 at high altitude). The fractional volume of the villi occupied by cytotrophoblastic cells and their nuclei number per 10 000 μm 3 of villous tissue were significantly greater in placenta from high altitude (3.17 and 1.86 per cent, respectively) than those from low altitude (1.05 and 0.79 per cent, respectively) ( P