Studies were performed to investigate the influence of long-term lead
acetate treatment on morphology of rat testis. No marked changes were
observed by means of light microscopy. At all stages (I-XIV) of the se
miniferous epithelium cycle, all generations and layers of spermatogen
ic cells were present. Electronmicroscopic studies did not reveal any
ultrastructural changes neither in seminiferous epithelium nor in Sert
oli cells. In Leydig cells also, no ultrastructural abnormalities were
visible. Macrophages of testicular interstitial tissue contained elec
tron-dense inclusions, usually located inside phagolisosome-like vacuo
les. X-ray micro-analysis revealed that the inclusions contained lead.