The syncytial knot: A sign of active syncytial proliferation

Abstract

A study of human placenta from normal and abnormal pregnancies was undertaken to examine the phenomenon known as “syncytial knotting.” Specimens from 65 abnormal pregnancies and 20 normal pregnancies from 8 to 43 weeks’ gestation were studied by phase contrast and light microscopy. Histologic evidence showed: (1) that these knots are proliferative areas of trophoblast better described as syncytial sprouts; (2) that there is a great morphologic similarity between the syncytial sprout as seen by phase contrast microscopy and the proliferative syncytium at the tip of a placental villus called ”bud” and the clumping of syncytial nuclei described as “syncytial knots” and the migrating trophoblast found in the maternal and/or fetal circulation ; (3) that there is no evidence of histologic degeneration in these sprouts; (4) that degeneration of the syncytium with nuclear degeneration and thinning, rupture, or complete disappearance of syncytial layer is a different process from syncytial sprouting. A study of human placenta from normal and abnormal pregnancies was undertaken to examine the phenomenon known as “syncytial knotting.” Specimens from 65 abnormal pregnancies and 20 normal pregnancies from 8 to 43 weeks’ gestation were studied by phase contrast and light microscopy. Histologic evidence showed: (1) that these knots are proliferative areas of trophoblast better described as syncytial sprouts; (2) that there is a great morphologic similarity between the syncytial sprout as seen by phase contrast microscopy and the proliferative syncytium at the tip of a placental villus called ”bud” and the clumping of syncytial nuclei described as “syncytial knots” and the migrating trophoblast found in the maternal and/or fetal circulation ; (3) that there is no evidence of histologic degeneration in these sprouts; (4) that degeneration of the syncytium with nuclear degeneration and thinning, rupture, or complete disappearance of syncytial layer is a different process from syncytial sprouting.