Lamella-particle complexes in the human placenta.

Lamella-particle complexes, similar in appearance to those found most abundantly in human hematopoietic malignancies, were seen within the cytoplasm of pericytes within the villus cores of 2 our ot 10 human placentas, 1 from a normal pregnancy and 1 from a pregnancy complicated by postpartum toxemia. Nine placentas were from term pregnancies, 6 normal and 3 complicated by toxemia, and 1 from a pregnancy complicated by premature delivery. The lamellae measured from 62-88 A in thickness and the particles from 175-220 A in diameter. The lamellae and particles were arranged in 3-6 apparently concentric layers around 0.08-0.24 micrometer diameter central cores to form complexes measuring from 0.37-0.75 micrometer in diameter. The complexes were infrequent, in pericytes and their presence did not appear to be correlated with either parity or any specific drug treatment. The reason for their presence in some human placentas is not known.