Effect of surgical restriction of growth of the testicular artery on testis size and histology in bulls.

The growth of the testicular artery was restricted on one side in young bulls and subsequent testicular development was monitored. After the animals had been killed, the testes were studied histologically and compared with testes from hypoplastic bulls. The growth rate of testes from the experimental side was significantly lower than that of testes from the sham-operated side over a period of 578 days. At death, the experimental testes had a mean (+/- SD) mass of 76 (+/- 41) g compared with 220 (+/- 31) g for the control testes. The sham-operated testes accounted for 0.071 (+/- 0.008)% of live body mass compared with 0.025 (+/- 0.014)% for the experimental testes. The seminiferous tubules in the sham-operated testes had a mean diameter (+/- SD) of 211 (+/- 25) microns, whereas those of the artery-restricted testes and hypoplastic testes were significantly smaller (152 (+/- 37) and 145 (+/- 45) microns, respectively). In the artery-restricted and hypoplastic testes, the interstitial tissue accounted for a significantly greater proportion of the testicular tissue than in the sham-operated testes and spermatogenesis was either totally absent or present in only a small proportion of tubules. It is suggested that the artery-restricted testes could be used as a model for testicular hypoplasia.