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 co mpared with material from 10 placentae delivered at low altitude (500 m). The sample groups were matched for maternal age, gestational age a nd parity. Within terminal and intermediate villi the volume-weighted mean cytotrophoblast cell volume did not significantly change at high altitude (754.1 mu m(3) at low altitude versus 796 mu m(3) at high alt itude). The fractional volume of the villi occupied by cytotrophoblast ic cells and their nuclei number per 10000 mu m(3) of villous tissue w ere significantly greater in placenta from high altitude (3.17 and 1.8 6 per cent, respectively) than those from low altitude (1.05 and 0.79 per cent, respectively) (P<0.0004 and P<0.0058, respectively). No sign ificant differences in either fractional volume of the syncytiotrophob last or its nuclei number per 10000 mu m(3) of villous tissue mere obs erved between placentae from high (26.01 and 11.6 per cent, respective ly) and low altitude (26.33 and 11.89 per cent, respectively). These r esults suggest an increase in the number of cytotrophoblastic cells at high altitudes without any changes in their volume. Exposure to hypob aric hypoxia is thought to be the principal aetiological factor. (C) 1 997 W. B. Saunders Company Ltd.