Interstitial cell proliferation in the testis of the ethylene dimethane sulfonatetreated rat

Abstract This study was conducted to examine interstitial cell proliferation in the testis of the ethylene dimethane sulfonate (EDS)-treated rat. Initial autoradiographic studies demonstrated a peak of [ 3 H]thymidine incorporation by interstitial cells at 2 and4 days post-EDS treatment. Subsequent studies were designed using in vivo pulse labeling regimens in an attempt to identify interstitial cell proliferation associated with Leydig cell regeneration. Rats were injected with [ 3 H]thymidine at days 2 and 4 post-EDS and were killed 6 hours later or at 30 days post-EDS. Although cells labeled at 2 and 4 days post-EDS appeared to undergo subsequent division, the Leydig cells visible at 30 days post-EDS were not labeled. In a second study, rats were injected with [ 3 H]thymidine at days 10 and 20 post-EDS and were killed either 6 hours later or at 24 days post-EDS. In the 10-day post-EDS group, interstitial cells were labeled at both the 6-hour and 24-day time points; however, Leydig cells present at 24 days were not labeled. In contrast, the testes of rats that were killed at 20 days post-EDS (6 hours labeling period) contained Leydig cells that displayed grains over the nucleus, thus suggesting that Leydig cell proliferation had occurred. In addition, a high number of the Leydig cells observed at 24 days post-EDS were labeled, suggesting that they arose from divisions occurring during the 20- to 24-day post-EDS period. These studies demonstrate that interstitial cell proliferation occurs in several stages following EDS treatment. The initial peak of [ 3 H]thymidine incorporation, which occurs immediately after EDS treatment, was not shown to be directly related to Leydig cell development. A second, but smaller, peak of proliferation that occurs between 20 and 24 days post-EDS is directly related to Leydig cell development.