Cell turnover in human seminal vesicles and the prostate: an immunohistochemical study

The human prostate and seminal vesicles are both androgen-dependent sex accessory organs. Their growth behavior, response to hormone manipulation, susceptibility to benign and malignant processes and sex accessory functions, however, differ greatly. The growth behavior of most tissues correlates well with the cell turnover rate of that tissue. Therefore, we compared the cell turnover of normal human prostate and seminal vesicles. Immunohistochemical expression of MIB-1 (proliferation), bcl-2 and transforming growth factor (TGF beta) were examined in 20 different samples taken from histologically normal human prostatic and seminal vesicle tissue. For the quantification of apoptosis, the TUNEL technique was used. The apoptosis rates in normal prostatic tissue (0.73+/-0.60) were significantly greater (P=0.003) than those seen in seminal vesicles (0.02+/-0.01). The proliferation rates also differed significantly (P=0.002) between these tissues (prostate: 0.77+/-0.78; seminal vesicles: 0.02+/-0.02). Eighty percent of the prostate tissue stained for bcl-2, whereas only 55% of the seminal vesicle tissue showed staining for bcl-2. All seminal vesicles and 75% of the prostate samples stained for TGF beta. For both androgen-dependent tissues, apoptotic rates closely equaled proliferation rates. The cell turnover, however, was much higher in the prostate than in the seminal vesicles. TGF beta seems to be more important for the regulation of cell turnover in the seminal vesicles than bcl-2. These differences in the proliferative behavior may explain why disturbances of apoptotic regulation lead to a more extensive net cell gain in prostatic tissue compared to the seminal vesicles. This might help explain the vastly different incidence of benign and malignant tumors in these organs.