Morphometric studies of compensatory testicular hypertrophy in the rat after hemicastration.

The quantitative nature of the compensatory testicular hypertrophy following unilateral castration was examined in groups of immature Wistar-derived male rats hemicastrated at 10, 20, 30, 40 and 50 days of age and completely castrated 20 days later. Hemicastration resulted in compensatory hypertrophy of the remaining testis and it decreased as the animals aged. In 30-day-old rats compensatory testicular hypertrophy was 33% while at 70 days of age hypertrophy was reduced to 2%. The increase in testis weight of hemicastrated rats was correlated with an increase in total seminiferous tubule length and a larger cross-sectional area which was due in part to the greater number of germ cells per testis. Sertoli cell number did not increase significantly in the hemicastrated testis but more germ cells were associated with each Sertoli cell.