THE EFFECT OF HYPOTHALAMIC LESIONS ON THE TESTES AND PROSTATE OF MALE DOGS12

Abstract

The effects of hypothalamic lesions on testicular function were studied in 21 mature male dogs. Destruction of the posterior median eminence (S dogs) resulted in testicular and prostatic atrophy without evidence of adrenocortieiil or thyroid inhibition. In these dogs, seminiferous tubule diameter and testicular and prostatic weight and histology were similar to those of hypophyscctomized dogs. One animal with a lesion involving the most caudal part of the posterior median eminence had atrophic seminiferous tubules and normal interstitial tissue. In 12 animals lesions did not involve the posterior median eminence, and testicular weight and histology were normal. Serial evaluation of sperm count and motility in 13 of the dogs with lesions revealed a prompt disappearance of motile sperms in four of the six animals with posterior median eminence lesions. In the other two dogs, spermatogenesis persisted for eight and 21 days respectively before declining to negligible levels. Four dogs with lesions in the anterior and middle median eminence showed a moderate decline in the number and motility of spermatozoa ejaculated, without atrophy of the gonads. Sperm count and motility remained normal in two of three dogs with normal testes and lesions sparing the median eminence. The significance of these findings is discussed.