Atrophy of seminiferous tubules of mouse testes after intratesticular injection of BCG and their regeneration.

Bacillus Calmette-Guerin (BCG) suspended in saline and given in a single intratesticular injection with uniform distribution at a dose of 10 units (1 unit containing 10(6) bacilli) was effective in inducing aspermatogenesis in mouse testes without affecting the Leydig cells. All tubules were free of spermatozoa 14 days after the treatment and remained so until 35 days. About 50% of the tubules did not have any germinal elements. Other tubules had mostly one or two layers of germ cells in the basal compartment. Full recovery of spermatogenesis was observed after 120 days. Proliferation of the residual germinal elements in the partially atrophied tubules was probably responsible for recovery, as the total number of tubules in BCG injected testes was 115 at 120 days (time of recovery) as compared to 258 in controls. The reduction in the number of tubules was compensated by a significant increase in the diameter of the tubules (118.4 +/- 3.23 micron in controls vs. 209 +/- 4.54 micron on recovery at 120 days), so that the overall size of the testes remained essentially unaltered.