Immunohistochemical localization of 6-keto-prostaglandin F1 alpha and prostaglandin E2 in the human umbilical cord before and after labor.

In this report immunohistochemical localization of 6-keto prostaglandin (PG)F1 alpha (the stable metabolite of prostacyclin (PGI2], PGE2, and its stable metabolite bicyclic PGE2 in umbilical amnion and vasculature is described. Umbilical cords were obtained at cesarean section from women who were not in labor (N = 7) and from women (N = 6) who went through normal labor and delivery at term. Study of both groups of umbilical cords allowed assessment of differential prostanoid metabolite localization pre- and post-labor. Formalin fixed, paraffin-embedded sections were stained by the avidin-biotin peroxidase complex method. PGE2, bicyclic PGE2, and 6-keto-PGF1 alpha localized to the amniotic cells covering the umbilical cord as well as to the endothelium of the umbilical veins in both groups (pre- and post-labor). No immunostaining was identified in the umbilical arteries. These findings suggest that amniotic cells and endothelial cells of the umbilical vein but not arteries are sites of synthesis or storage for the prostanoids 6-keto-PGF1 alpha and PGE2.