PHENOTYPE OF CULTURED FETAL PERIVASCULAR CELLS FROM HUMAN PLACENTA STUDIED BY SCANNING ELECTRON-MICROSCOPY

The phenotype of perivascular placental cells has previously been stud ied using tissue sections from the fetal villi. The examination of the se cells in culture by scanning electron microscopy gives us the oppor tunity to observe their three-dimensional phenotypes and associations outside their normal constraints. Human umbilical endothelial cells, w hich have a phenotype comparable to that observed in other studies, se em more flattened in culture than in their usual environment. Microvas cular endothelial cells did not attain an epithelioid phenotype with c lose contacts between cells but formed a network of branched, elongate d cells with phagocytotic activity. Some circular associations were ob served when using a gelatinized matrix. Microvascular pericytes were l arge, flattened cells with an irregular border that pushed up nodular associations on a gelatin matrix. Chorioplacental myocytes adopted a n etwork template comparable to that developed by microvascular endothel ial cells. However, these elongated cells were thicker, without microv illi, and superficial filaments could be observed.,In culture, conflue nt endothelial cells from the umbilical cord or microvascular pericyte s associated as nodules reached a cell phenotype close to their in viv o counterparts. This attainment of an in vivo phenotype remains questi onable for chorioplacental myocytes. Microvascular endothelial cells, however, though there was sparse formation of circular associations, r emained far from their in vivo phenotype.