The effect of high-dose medium- and long- term progestogen exposure on endometrial vessels.

A total of 19 paraffin-embedded endometrial tissue blocks were obtained from high-dose progestogen-exposed patients. A labelled streptavidin-biotin-alkaline phosphatase method was used with antibodies against von Willebrand factor (vWF) and CD34. The density of CD34 and vWF positive (CD34+ and vWF+) vessels in progestogen-exposed endometria (103 +/- 9.6/mm2 and 106 +/- 8.7/mm2) was significantly lower than in endometria from women with normal cycles (169 +/- 9.3/mm2 and 136 +/- 8.0/mm2) (P < 0.05). In women with normal menstrual cycles the concentration of CD34+ vessels was significantly higher than the number of vWF+ vessels (P = 0.0001). By comparison, the concentration of CD34+ vessels was similar to the concentration of vWF+ vessels in progestogen-exposed endometria. The ratios of vascular density as determined by vWF+ and CD34+ staining the control and progestogen groups were 0.81 and 1.05 respectively (P = 0.0001). Dilated venules were seen in the progestogen group. This study has demonstrated firstly that CD34 antibody detected the endothelial cells in a higher proportion of small endometrial vessels than vWF, and secondly that high-dose progestogen exposure significantly decreased the density of microvessels and increased the number of dilated venules in endometrium.