Ultrastructural, morphometric, and hormonal analysis of the effets of testosterone treatment on Leydig cells and other interstitial cells in young adult rats

Early effects of testosterone (T) treatment on the ultrastructure of testic ular interstitium were analyzed by morphometry. In T-treated young adult ra ts the T-LH feed-back loop functioned as expected and the marked increase i n peripheral T caused almost complete depletion of peripheral LH. Even thou gh the peripheral LH concentration was almost undetectably low, the Leydig cells maintained regulatory interactions with macrophages, peritubular myoi d cells and with the seminiferous epithelium lining the tubular lumina as i ndicated by the high correlations of morphometric parameters between the Le ydig and other cell types. The morphometric alterations in the ultrastructu re of Leydig cells suggest that the seminiferous tubules may signal by rele asing inhibitory paracrine factors affecting the morphology and function of Leydig cells in T-treated young adult rats. The morphometry of Leydig cell s in T-treated young adult rats showed a significant quantifiable reduction in nuclei and organelles involved in steroid synthesis and this analysis a lso offers a good basis for elucidation of the early effects of testosteron e in terms of its contraceptive function as well as of different toxic comp ounds on reproductive functions.