Age changes in density of endometrial stromal cells of the rat

Stromal cells were counted in the endometrium of the rat during aging. Cell counts were made in the subepithelial, middle and deep regions of the endometrium in the left uterine horn of virgin Sprague-Dawley rats at 36 days of age and at 4, 10, and 20-24 months. In all regions of the endometrium the density of stromal cells decreased with aging. Decrease in cell numbers per unit area was greatest in the middle and deep endometrium. In 20 to 24-month-old rats, the mean number of cell profiles within 0.085 mm2 of the middle endometrium had decreased to less than one-third the number that was present within the same area in the 36-day animal. In the deep endometrium of these oldest rats, the mean number of cells had decreased to less than one-fourth. An age-associated decrease in density of stromal cells may contribute to alterations that have been observed in hormone-dependent uterine synthetic activities during aging.