Chemical sterilization of male dogs after a single intra-testicular injection of "Danazol".

The effects of chemical sterilization with a single injection of Danazol a synthetic (23-isoxazol) derivative of 17-alpah-ethinyl testosterone into the right testis of male dogs were studied. Disorganization of the seminiferous epithelium and interstitium oedema and shrinkage of the nuclear diameter of tubular and Leydig cells were observed in the treated testis. RNA synthesis and sialic acid concentrations were diminished. Alkaline phosphatase activity was stimulated and levels of testicular cholesterol and total lipids were significantly increased (p less than .01). Testicular atrophy and/or decreased production of androgens could explain the increase in cholesterol levels. The reduction in nuclear diameter of Leydig cells was also correlated with decreased androgen production. The results indicate that Danazol injection completely destroys the seminiferous epithelium gross interstitum oedema and Leydig cells.