Role of thyroid in testicular development of immature rat.

Prepubertal spermatogenic cells in immature rats show pronounced dependency on thyroid hormone. In thyroidectomized immature male rats widespread regression of these cells were observed. These changes could be prevented by administration of small doses of thyroxine. In unthyroidectomized immature rats, thyroxine in the same dosage, caused an increased degree of growth and development of testicular tissues as compared to control.