The surface morphoIogy of normal term amnion was studied by scanning electron microscopy. Four patterns were observed. Two of the patterns showed distinctive minority populations of cells. In one, there were cells surrounded by intracellular channels; in the other, there were large flat cells. The microvilli in all four patterns showed variable morphology in different samples. Possible functional implications of the findings are discussed.

The appearances of the amnion from two patients with polyhydramnios and two patients with oligohydramnios are described. In polyhydramnios the amnion showed a normal incidence of all the four patterns found in normal amnion at term and no abnormal features were noted. In oligohydramnios, two of four normal patterns predominated and intercellular canals were sparse.