AN IMMUNOHISTOCHEMICAL STUDY OF THE VASCULARIZATION OF THE HUMAN GRAAFIAN FOLLICLE

The wall of the largest Graafian follicle or corpus luteum was biopsie d in 22 patients at laparoscopy. Both granulosa and theca cells were c ontained in 18 samples. These samples were classified as pre-luteinizi ng hormone (LH) surge (n = 3), LH surge (n = 3), early luteal (n = 3), mid-luteal (n = 4), late luteal (n = 3) and menstrual (n = 2). A doub le-staining immunohistochemical protocol was used to demonstrate proli ferating endothelial cells: mouse-anti-rat-proliferating cell nuclear antigen, for proliferating cells; mouse-anti-human-CD34 antibody for e ndothelial cells. The percentage of endothelial cells proliferating (p roliferation index) and the area of tissue occupied by endothelial cel ls (areal fraction) were determined for granulosa and theca layers. In tra- and inter-slide coefficients of variation were < 15%. The granulo sa layer was avascular until the LH surge subsided. Maximum vasculariz ation was achieved by the mid-luteal phase. The theca endothelial cell proliferation index was constant from pre-LH surge to mid-luteal phas es. The mean theca endothelial cell proliferation index for these phas es was significantly greater than for the late luteal and menstrual ph ases. From first appearance in the granulosa layer, endothelial cells had the same proliferation index as the theca endothelial cells, the p roliferation index decreasing significantly in both after the mid-lute al phase (P = 0.018). It is concluded that endothelial cell proliferat ion is unchanged throughout the follicular, early and mid-luteal phase s, decreasing significantly in the late luteal phase. By contrast, end othelial cell invasion of the membrana granulosa, presumably in respon se to a chemotactic stimulus, occurs after the LH surge has subsided.