The principal and probably sole function of the prostate gland and seminal vesicle is to secrete the bulk of the seminal plasma. The physiology of these organs is, therefore, of obvious importance in fertility. But there are many other reasons why study of the accessory glands is of the widest medical and biological moment. Their normal growth, differentiation, and function are governed primarily by testicular hormones, and they provide ideal material not only for the bioassay of androgenic hormones but also for investigation of the actions of androgens at a cellular and molecular level. Benign hypertrophy of the prostate is one of the commonest of neoplasms in the male. The most prevalent cancer in older men is carcinoma of the prostate gland. Sexual hormones are profoundly involved in the etiology and natural history of both benign and malignant prostatic neoplasms. The ability of estrogens to cause shrinkage and temporary cessation of growth of many prostatic cancers is now a commonplace of cancer chemotherapy.

Considerable attention had been paid in this laboratory to the biochemistry and hormonal control of the accessory glands and their secretions.

Prostatic Secretion In The Dog

The cardinal importance of sex hormones for the functional goings-on in the male accessory glands was made clear more than twenty years ago from studies of the secretion of the canine prostate gland. The dog is devoid of both seminal vesicles and bulbo-urethral glands, and, if the urine is suitably deviated, practically pure prostatic secretion can be collected from the urethra. A prostatic isolation operation (Huggins, C; Masina, M. H.; Eichelberger, L.; and Warton, J. D. J. Exper. Med., 70:543, 1939), devised in 1939, enabled frequent collection of canine prostatic fluid over long periods of time (Fig. 16). After a cholinergic stimulus, the output of prostatic secretion could be followed volumetrically. In 1953 (65), the prostatic isolation operation was modified for the better, and a novel surgical procedure (prostatic translocation) was developed whereby the canine prostate was transposed from its natural position to the perineum (Fig. 17). This enabled the size of the prostate to be measured in the living animal and allowed the collection (after dosage with pilocarpine) of prostatic fluid which was quite uncontaminated with other material. The secretion of the submaxillary gland, obtained through a fistula, was used as an internal biologic standard of the secretory stimulation by pilocarpine. Prostatic size and secretion were affected gready by androgenic and estrogenic substances, in contrast to salivation. In castrate dogs, the augmentation of prostatic volume and secretory activity by testosterone was, under certain circumstances, proportional to the amount of androgen administered. Stil-bestrol counteracted the effects of testosterone, and the reverse was also true. The experiments with dogs subjected to prostatic translocation fully corroborated earlier and more extensive studies on the hormonal control of prostatic function involving the prostatic isolation operation (cf. Hug-gins, C. The Harvey Lectures, 42:148, 1947).

Fig. 16.-The canine prostatic isolation operation. The connection of the prostatic urethra with the bladder has been severed, and the prostatic secretion is collected by way of the penis (6s).