Weight, stroma to gland ratio, and mitotic activity of the human hyperplastic prostate.

The growth of the hyperplastic prostate of 12 patients was studied with an in vitro 3H-thymidine labeling method. The prostates were weighed and the stroma to gland ratio was analyzed. The mitotic activity of the glandular epithelium averaged 0.36 per cent (+/- 0.06 SE). No mitotic activity was found in the stromal tissue. There was a positive correlation between the weight of the prostate and the labeling Index of the glandular epithelium. Thus, the prostatic hyperplasia of these patients appeared to be purely glandular in form. The stroma to gland ratio was 70 to 80 per cent. It was found that most of the glandular follicles were mitotically quiescent, and that the mitotic activity was concentrated in a few of the follices. The results indicate that the growth of the hyperplastic prostate is caused both by the mitotic activity (hyperplasia) of the glandular epithelium and by the stromal hypertrophy. Thus, in vitro assay of the mitotic activity of the prostatic biopsies can be used for the estimation of the weight of the hyperplastic prostate. The possible role of the stroma in regulation of the mitotic activity of the glandular epithelium has been discussed.