EFFECTS OF ACTIVE LABOR ON THE ULTRASTRUCTURE OF AMNION EPITHELIUM

The study was conducted at Zeynep Kamil Women and Children's Hospital and Marmara University Department of Histology and Embryology to inves tigate the effects of active labour on the ultrastructure of amnion ep ithelium. Among patients between 38 and 41 weeks of gestational age, w ho were randomly chosen, 15 delivered by elective caesarean section be fore the onset of labour and 10 delivered after the onset of labour by the normal route or caesarean section. The placenta and membranes wer e collected from each subject and 1 mm(3) from each was studied by lig ht, transmission and scanning electron microscopy. Some specimens were stained by lipid dyes to determine lipid fractions. In the group with out active labour the surface of the epithelium was indented with high collumnar cells. There were numerous microvilli. Scanning electron mi croscopy showed a polygonal mosaic domed structure. The amnion cells h ad phospholipid granules in some areas when the specimens were stained by lipid dyes. In the group which had active labour, transmission ele ctron microscopy showed that the amniotic epithelium interchanged betw een cubic and squamous, there were fewer microvilli, intercellular jun ctions were looser and the cells contained multiple lipid vesicles. On scanning electron microscopy, there were intercellular fissures with depressions in their centres. The lipid granules were spread diffusely in the amnion cells as shown by lipid dyes. We conclude that the ultr astructural changes in amnion epithelium after the onset of labour sug gest it has an active role in triggering the onset of labour. (C) 1998 Chapman & Hall Ltd.