Scanning electron microscope appearances of normal human amnion and umbilical cord at term.

The surface morphology 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.