EFFECT OF SEMINIFEROUS TUBULE SIZE ON HCG-INDUCED REGENERATION OF PERITUBULAR LEYDIG-CELLS IN HYPOPHYSECTOMIZED, EDS-TREATED RATS

Following their selective destruction 3 weeks previously by administra tion of ethane dimethanesulphonate (EDS) the regenerative capacity of Leydig cells was assessed in relation to seminiferous tubule morpholog y in hypophysectomized adult rats administered 7 daily injections of 1 00 iu hCG. Total Leydig cell volume per testis in hCG-treated rats (30 .2 +/- 3.2 mu l, mean +/- SEM) was significantly (p<0.01) greater than in the testes of rats at 3 and 4 weeks after EDS-treatment (7.6 +/- 0 .7 and 22.7 +/- 1.4 mu l, respectively). Regeneration of Leydig cells in hCG-treated rats significantly (p<0.05) favoured peritubular locati ons (18.6 +/- 2.8 mu l/testis) compared to central or perivascular sit es of origin (11.6 +/- 1.2 mu l/testis). Partial restoration of sperma togenesis occurred in hCG-treated rats (tubule diameters usually >250 mu) and a significant inverse correlation was found between peritubula r Leydig cell percentage,or total volume per testis, and the volumetri c proportion of seminiferous tubules (r=-0.94, p<0.001) or the seminif erous epithelium (r=-0.73 to -0.79, p<0.05-0.01). No significant (p>0. 4-0.9) correlation existed between centrally-regenerate Leydig cells a nd these parameters. The results show that in response to hCG stimulat ion, Leydig cells are more likely to develop around smaller seminifero us tubules, suggesting that hCG alone cannot mimic the expected patter n of Leydig cell regeneration (central and peritubular origins) which occurs during normal sexual maturation or at 3-4 weeks after EDS treat ment. It is concluded that other factors, possibly FSH, are required f or typical Leydig cell development which in turn may be influenced by local cellular growth factors originating from either the seminiferous tubules or the adjacent intertubular tissue.