Effects of estrogen and progestin replacement on the urogenital tract of the ovariectomized cynomolgus monkey.

Menopause is presumed to have a causative role in the development of female urinary incontinence. While some clinical trials have shown that estrogen can affect urinary tract function, our knowledge of the pathophysiologic changes resulting from menopause and hormone replacement therapy is poor. The cynomolgus monkey is a well-established model for study of menopause and hormone replacement therapy, particularly in the cardiovascular arena. We have utilized this animal model to determine the histologic effects of estrogen and estrogen/progestin replacement therapy in the proximal urethra and vagina. Estrogen and estrogen/progestin replacement induced an increase in the amount of vaginal but not urethral epithelium. Hormone replacement also resulted in a significant increase in the loose, vascular component of the connective tissue layer of the urethra. The cynomolgus macaque shows promise as a useful model for further study of the effects of hormone replacement on the lower urinary tract.