Significance of changes in fetal perfusion pressure to factors controlling angiogenesis in the human term placenta.

The objective of the study was to determine the effects of mechanical factors on endothelial proliferation in the human placental villous vasculature. Individual fetal lobules were perfused with tissue culture medium at two different standard pressures (40 and 100 mm Hg). The perfused area was then removed and diced into small blocks which were quench frozen in liquid nitrogen. Cryostat sections were obtained and fixed in acetone at 4 degrees C. Proliferating cell nuclear antigen was then identified using Ki67 antibody as a marker. Proliferating nuclei were scored, using a light microscope, and a comparison made between the two pressures used. More proliferating endothelial nuclei were found at 100 mm Hg than at 40 mm Hg (P < 0.05). It is therefore concluded that mechanical factors may play a role in villous angiogenesis and the formation of terminal villi.