Age difference in the prostate hypertrophy induced by the removal of the seminal vesicle in rats.

The removal of the seminal vesicle in 4-week-old, 6-week-old or 1.2-year-old rats resulted in a significant increase in the weight of the lateral prostate 6 weeks later examined. The weight change was mainly due to a marked distension of alveoli but showing close resemblance to structures of the control animals with secretory activity. RNA/ DNA ratio in the unit tissue increased. Constricted alveoli and epithelial hyperplasia in many alveoli were demonstrated after removal of the seminal vesicle only in the lateral prostate of aged rats, though a less marked change :in the weight was shown. The degree of the hypertrophy of the prostates was largely dependent on the age of rats. The greatest increase in the weight of both lateral and ventral prostatic lobes was observed when the seminal vesicle was removed at 4 weeks of age. More than one hundred per cent, 94% and 48 % increase in the weight of the lateral prostate over the control values were shown in immature, young adult and aged rats respectively. The weight of the ventral prostate also increased after removal of the seminal vesicle but to a lesser extent as compared to that seen in the lateral prostate. No response of the ventral prostate to the ablation of the seminal vesicle was found in aged rats. Factors which might be involved in the cause of the prostate hypertrophy in absence of the seminal vesicle were discussed.