Cell surface lipid in the amniotic fluid.

Limitations of cell staining and light microscopy have led to confusion as to the etiology and morphologic characteristics of nile-blue-sulfate-stained orange cells in amniotic fluid. Nomarski Differential Interference Contrast Microscopy (NDICM) was used to study these cells as they appear in their unstained state. The presence of lipid-bearing cells was correlated with gestational age and mode of delivery, and incubation studies were applied toward an evaluation of the mechanism of lipid formation. Lipid-bearing cells in the amniotic fluid appeared after 37 1/2 weeks' gestation in association with fetal lung maturity.