Longitudinal growth of the seminiferous tubules in LH and FSH treated rats.

New born Sprague Dawley rats were injected daily either with 50 (n=8), 100 (9) or 200 (10) mug FSH; with 50 (9), 100 (5), 200 (10) mug LH; with a combination of 50 mug FSH + 50 mug LH (10); or with the vehicle 0.9% saline (10). The animals were sacrificied at an age of 16 days. There was no influence of the hormones on the body weight. FSH caused a dose dependant stimulation of the testes growth (163, 186, 227 mg for the 50, 100 and 200 mug group; control 139 mg; diff. to control P less than or equal to 0.05, 0.01, and 0.01), whereas LH had no effect (123, 154 and 133 mg for the 50, 100 and 200 mug. LH group). The weight of the seminal vesicles was increased slightly by LH only (Diff. to control P less than 0l01). The serum androgen level was not changed by any of the treatments. The stage of the spermatogenesis was not altered by the hormones. There was no significant difference in the diameter of the seminiferous tubules. The higher testes weight after FSH administration was caused by an increase of length of the seminiferous tubules (25 m, 30 m and 35 m for 50 mug, 100 mug, and 200 mug FSH; control 23 m; diff.: P less than or equal to 0.05, less than or equal to 0.01, less than or equal to 0.01). The conclusion is that FSH has a specific effect on the longitudinal growth of the seminiferous tubules in prepubertal rats.