Histological and ultrastructural analysis of the seminiferous tubule wall in ageing testis.

The authors evaluated possible morphological changes of basement membrane (BM) and lamina propria (LP) of seminiferous tubule wall (ST) related to ageing. Surgical samples of testicular tissue from 28 cases with orchiectomy for prostate adenocarcinoma were processed for light microscopy and transmission electron microscopy (TEM) examination. Seven age groups (AgGr) between 50 and 80 years were designed. Tissue samples were immunomarked for collagen IV and smooth muscle actin. Images were acquired and measured with a specialized software. Thirty ST were randomly selected, with ×40-objective, for each case. Five random determinations for each ST and each parameter were performed. Mean values/tubule, case and AgGr were calculated for each parameter. Regression line (RL), slope and significance test for slope were determined for each parameter correlation with ageing. BM mean value was around 0.5 μm, with narrow limits of ranging in AgGr but more extended individual limits. RL showed discrete decreasing trend with ageing but without an obvious statistical correlation. LP mean value was around 6 μm, also with narrow limits of ranging in AgGr and more extended individual limits. RL decreased discretely with ageing but without an obvious statistical correlation. TEM showed more prominent BM material and more collagen fibers and less fibroblasts in LP of older AgGr and higher fibroblasts density in LP of younger AgGr. Our results showed that BM thickness is apparently decreasing with ageing whereas LP presents extremely variable degenerative changes, with a "mosaic", focal distribution and no tendency to advance with ageing.