Possible role of elongated spermatids in control of stage-dependent changes in the diameter of the lumen of the rat seminiferous tubule.

Adult male rats were treated with a single dose of 650 mg/kg methoxy acetic acid to deplete the seminiferous tubules specifically of pachytene and later spermatocytes. The effect of this treatment and the subsequent maturation-depletion of later germ cell types on the diameter of the seminiferous tubule and its lumen and the area of the seminiferous epithelium were studied in relation to the stages of the spermatogenic cycle. At 21 days after methoxy acetic acid treatment, the diameter of the tubule and the area of the epithelium were reduced below control values at all stages, consistent with the reduced number of early (stage VIII) or late (all other stages) spermatids. Unexpectedly, diameter of the lumen was also reduced at all stages other than VIII, and especially at stage VII. In controls, lumen diameter at stages VII and VIII was increased by approximately 50% compared with earlier and later stages. In rats treated 21 days previously with methoxy acetic acid no change occurred at stage VII (lacking elongated spermatids) while a normal increase did occur at stage VIII (lacking round but not elongated spermatids). At earlier times after methoxy acetic acid treatment when stage VII tubules were depleted of pachytene spermatocytes alone (3 days) or together with early spermatids (7 days), the diameter of the lumen was not significantly different from the control value. These data suggest that lumen diameter may be regulated by elongated spermatids, especially at stages VII and VIII.