Regulation of endometrial angiogenesis.

Bleeding problems are the most common reason for discontinuation of hormone replacement therapy. Human endometrium undergoes the unique process of benign angiogenesis under the control of ovarian steroids during reproductive life and it is presumed that similar processes occur when women take hormone replacement therapy. The key players in endometrial growth and angiogenesis are vascular endothelial growth factor, thymidine phosphorylase and adrenomedullin. Regulation of these angiogenic factors is described.