Quantitative histological analysis and ultrastructure of the aging human testis

Purpose To quantitatively assess the histological and ultrastructural changes resulting from aging in the human testis. Methods Age-related histological and ultrastructural changes were evaluated using light microscopy, transmission electron microscopy (TEM) and immunohistochemistry on 41 testicular samples obtained from elderly men and, respectively, assigned to group A ( n = 20), 54–69 years old or group B ( n = 21), 70–89 years old. Testicular samples derived from 17 young men were used for control. Results The numbers of Sertoli cells in the aged groups were significantly lower than that in the controls ( p < 0.05). With the exception of the Sertoli cell ratios (germ cells/Sertoli cells) of spermatogonia and primary spermatocytes, results showed lower levels of the Sertoli cell ratios of round spermatids and elongated spermatids in the elderly men compared with the young men ( p < 0.05). A similar degenerative pattern of the organelles was shown in germ cells and Sertoli cells in the aging testes under TEM. Immunohistochemistry revealed an increased apoptosis index (AI) (0.81 ± 0.13) accompanied by a decreased proliferation index (PI) (30.08 ± 4.86) in the group B ( p < 0.05), while both AI and PI were similar between the group A (0.54 ± 0.06; 36.38 ± 7.38) and the controls (0.50 ± 0.15; 40.55 ± 7.92) ( p > 0.05). Conclusions Aging has negative influence on testicular morphology and spermatogenesis, and the failure of spermatogenic cell development is evident from the spermatid level.