Maintenance of adult rat ventral prostate in organ culture

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Abstract
Androgens postpone the involution of prostatic tissue cultured in a chemically defined medium. However, after 1 week quantitative changes are accentuated and qualitative signs of involution appear. Other factors in addition to androgens are obviously needed for the adequate maintenance of the tissue. This study was aimed at the improvement of the culture conditions by adding insulin, corticosterone, epidermal growth factor, prolactin, and transferrin alone or in different combinations with testosterone and each other. A morphometric model developed for prostate culture was used, and maintenance and proliferation of the tissue were further followed by weighing the cultured explants and by measuring the incorporation of (3H) thymidine into DNA. The androgen dependency was seen in all the studied morphometric parameters at least for 2 weeks–i.e., in volume density and height of epithelium (VVEP and h), reflecting the epithelial maintenance, in volume density and width of interacinar tissue (VVIT and λAP), reflecting stromal tissue, and in volume density and diameter of lumen (VVLU and DLU), reflecting the secretory function. Testosterone (10−7 M) also prevented partially the quantitative involution of the tissue within 2 weeks. Insulin, acting independently of androgen, was a potent mitogen, which, according to morphometric results, exerted its effect mainly on prostatic epithelium. Stratification of epithelium was frequently seen. Corticosterone had no effect on epithelian proliferation, but it probably stimulated secretion and inhibited the growth of stroma. By combining these three hormones it was possible to maintain not only the structure but also the amounts of tissue components practically unaltered at least for 2 weeks. Epidermal growth factor (EGF) and prolactin had only marginal effects, and transferrin had none. It remains to be settled whether these three factors are needed for the prostate in long-term cultures.