The karyopyknotic index of amniotic fluid cells and its relationship to oestrogen concentration

Estimations of karyopyknotic index and amniotic fluid oestrogen concentration were made on 107 specimens of amniotic fluid obtained between the 25th and 42nd weeks of pregnancy. The karyopyknotic index was shown to fall with advancing gestation as the amniotic fluid oestrogen concentration increased. The negative correlation between karyopyknotic index and amniotic fluid oestrogen concentration was highly significant when the fetus was female but was not significant when the fetus was male. Intermediate cells from the gential tract of the female fetus can account for the cytological difference between amniotic fluid from male and female fetuses. The fall in amniotic fluid karyaryopyknotic index towards term which suggests that the fetal vagina responds in the same way as the maternal vaginal epithelium to the circulating hormones and not to the oestrogens in the amniotic fluid.