Amniotic epithelial ultrastructure in normal, polyhydramnic, and oligohydramnic pregnancies.

The ultrastructure of the amniotic epithelial cells from normal, polyhydramnic, and oligohydramnic pregnancies were studied with the transmission electron microscope. The amniotic epithelial cell layer from normal pregnancies was 8- to 12-mu thick. In polyhydramnic pregnancies the cell layer varied widely from the normal thickness to as much as 18 to 56 mu in diabetic patients. Other ultrastructural changes observed in pregnancies complicated by polyhydramnios were abnormal microvilli, diminished intercellular canals, increased tonofilaments, and decreased rough-surfaced endoplasmic reticulum. In pregnancies complicated by oligohydramnios the thickness of the cell layer was 3 to 6 mu. The amniotic epithelial cells had increased tonofilaments, decreased desmosomes, collapsed and fused intercellular canals, and caused a marked decrease of the Golgi apparatus and the rough-surfaced endoplasmic reticulum. The sparse microvilli were short, plump, and had bizarre shapes.