EPITHELIAL DEVELOPMENT IN THE RAT VENTRAL PROSTATE, ANTERIOR PROSTATEAND SEMINAL-VESICLE

The prostate and seminal vesicle (SV) are androgen-dependent secretory glands of the male genital tract. The epithelial cells of these gland s produce the bulk of the seminal secretions. The objective of the pre sent study was to examine the ontogeny of cytokeratin and androgen rec eptor (AR) expression in the rat SV, anterior prostate (AP) and ventra l prostate (VP). The study utilized organ culture to examine the effec ts of androgens on the development of these markers and castration of adult rats to examine androgenic effects on their maintenance. Tissues were examined from 14 days of gestation to adulthood. The SV was a tu bular organ from its inception while the prostate formed from solid ep ithelial cords. These prostatic buds canalized in a proximal to distal manner starting at day 1 postnatal in the VP and day 5 in the AP The expression of cytokeratins and AR was visualized by immunocytochemistr y. In all three glands keratins 5, 7, 8, 14, 18 and 19 were initially uniformly expressed in all epithelial cells. In the SV, segregation of cytokeratins between the luminal and basal cell types started at 4 da ys postnatally with keratin 7 localizing to basal cells. Five days aft er birth, keratins 5 and 14 were also localized to the basal epitheliu m, while keratins 8 and 18 were only expressed by luminal cells. Kerat in 19 was expressed in all epithelial cells throughout development and into adulthood. In the VP and AP the same pattern of cytokeratin segr egation occurred as in the SV. Epithelial differentiation occurred in a proximal to distal fashion in the prostate. In the proximal VP ducts keratins 7 and 14 were basally localized by 2 days postnatally, while keratin 5 did not clearly segregate to basal cells until day 9 after birth. In the AP keratin 14 was basally localized by 1 day postnatal b ut keratin 5 and 7 did not colocalize to the basal cells until days 9 and 12, respectively. AR were expressed in the epithelium of the uroge nital sinus from 19 days of gestation. At 19 and 20 days of embryonic development AR-negative prostatic buds were seen emerging from the AR- positive urogenital sinus epithelium. By birth AR were delectable in t he epithelium of both prostatic lobes and the SV. The role of androgen s in the development of the prostatic and SV epithelium was investigat ed in a serum-free organ culture system. These experiments showed that differentiation of prostatic and SV luminal and basal epithelial cell types was accelerated as compared to the in vivo situation in the pre sence of androgens, and did not occur in their absence. Following cast ration of adult animals the prostate and SV regressed with preferentia l loss of luminal epithelium. The relative numbers of basal cells was increased, though some flattened cells expressing a luminal cell patte rn of cytokeratins were still observed. AR were detected in the prosta tic and SV epithelium of longterm castrated animals. In summary, the r at prostate was found to be derived from undifferentiated solid epithe lial cords. Canalization occurred concurrent with the differentiation of clear epithelial subtypes. Epithelial AR were expressed from around the time of birth and expression levels increased with age. The SV wa s canalized from its inception but likewise was derived from an undiff erentiated epithelial precursor.