Chalones and stroma as possible growth-limiting factors in the rat ventral prostate

In an attempt to determine the mechanism that limits the growth of the rat ventral prostate, atrophied ventral prostates from orchiectomized inbred rats were implanted into the ventral prostate of other inbred rats. Under the influence of endogenous or exogenous androgen the DNA content of the ventral prostates was increased above normal. This indicates that there is no soluble growth inhibitor diffused in the normal prostate in a concentration sufficient to block cell divisions of the epithelial cells. In other experiments pieces of plastic sponge were implanted into the rat ventral prostate. Orchiectomy and subsequent androgen treatment led to an increased cell number in the prostate. Histologic examination revealed an ingrowth of loose connective tissue and also of normal-looking prostatic tissue in the sponge. The results suggest that implantation of pieces of sponge induced increased growth of the fibromuscular stroma and a secondary proliferation of the epithelial cells. A growth control of the prostatic epithelial cells by the fibromuscular stroma is suggested.