AGE-RELATED MORPHOMETRICAL CHANGES OF ARTERIES OF UTERINE WALL IN MARES

To investigate the morphological changes of uterine wall arteries asso ciated with the progression of age in Thoroughbred broodmares, uterine wall arteries from 13 mares, aged 2 to 31 years, were studied by rout ine histomorphometry. The ratio of intimal thickness to external diame ter increased due to hyperplasia of elastic fibers and was significant ly correlated with age (r = 0.95, < 0.001). The ratio of medial thickn ess to external diameter decreased and was also significantly correlat ed with age (r = -0.84, P < 0.001). Using electron microscopy, it was determined that the cross-sectional area of the tunica media occupied by smooth muscle cells gradually decreased with increasing age. These results demonstrate that in arteries of the uterine wall in mates, hyp erplasia of intimal elastic fiber and thinning of the medial smooth mu scular layer is associated with aging, suggesting that aging may influ ence endometrial pathology.