Morphological and immunohistochemical characteristics of the heterogeneous prostate-like glands (paraurethral gland) seen in female Brown-Norway rats.

Morphological and immunohistochemical characteristics of the prostate-like glands (paraurethral gland) seen spontaneously in female Brown-Norway (BN) rats were investigated by gross, and light and electron microscopic examination. At 9- to 10-weeks-old, the paraurethral gland was detected in 50 out of 52 female animals examined (96.2%), and it was observed as single or paired structures located ventrolaterally in the urethra just caudal to neck of the urinary bladder. Microscopically, the glandular acini consisted of flat to cuboidal secretory epithelium surrounded by the smooth muscle. The glands displayed modest secreting activity, and a few secreting materials were observed in the acinar lumens. The main peripheral ducts were located in the urethral wall, and drained into the urethra on both sides. Ultrastructurally, abundant rough endoplasmic reticulum (RER), numerous mitochondria and lysosomes, and secretory granules in the apical portion of the epithelial cells were noted, and basal cells were also observed. These gland epithelial cells showed positive reactions when stained for androgen receptor (AR), prostate specific antigen (PSA), or prostate specific acid phosphatase (PSAP). The nature of this paraurethral gland resembled that of the prostate gland in male rats. Thus, the paraurethral glands seen in the females were considered homologous to the prostate gland in males.