Quantitative morphology of the placenta. II. The growth of the placenta and the problem of postmaturity.
The morphological changes in the placenta concomitant with the transition from maturity to postmaturity were investigated by stereology under early clamping of the umbilical cord. 37 placentas from nonpathological pregnancies delivered after a period of 224-303 days of amenorrhea were examined. It appeared that after 267-288 days of amenorrhea, 8 out of 9 placental components showed no further growth and even showed regression. Only the volume of the trophoblast continued to grow in postmaturity. It is suggested that during postmaturity the villous capacity to produce steroids is continuing at a normal rate (as judged by the increase of the volume of the trophoblast), whereas the capability to transfer is deteriorating (as testified by the decreasing surface of the trophoblast).
D002824:Chorionic Villi / Q000473:pathology; D005260:Female; D006801:Humans; D010920:Placenta / Q000473:pathology*; D011247:Pregnancy; D011273:Pregnancy, Prolonged; D013997:Time Factors