ACCESSORY MAMMALIAN REPRODUCTIVE GLANDS 



369 



mals, but it is rather doubtful if their ab- 

 sence is related to an aquatic environment. 

 BuLBOVESTiBULAR (Bartholin's) . The 

 bulbovestibular or major vestibular glands 

 are also compound tubulo-alveolar glands 

 which resemble their male homologues in 

 structure and secrete a mucus-like sub- 

 stance. Their secretory function is under 

 control of ovarian hormones and they in- 

 volute when the ovaries are removed. They 

 are widely distributed in the various orders 

 of mammals although the information is 

 fragmentary with respect to some groups. 

 A single pair of glands is the general rule 

 and they are usually much smaller than the 

 bulbo-urethral. In the female opossum, the 

 single pair of glands is homologous with the 

 smallest of the three pairs of Cowper's 

 glands. In the adult, they are well developed 

 and filled with colloid (Rubin, 1944). In 

 monotremes the ducts open at the base of 

 the clitoris, in opossums into the urogenital 

 sinus canal, and in hyenas (where they are 

 well developed) into the urogenital canal 

 close to the base of the clitoris (Eckstein 

 and Zuckerman, 1956). In many other fe- 

 males the ducts open into the vestibule. In 

 the adult human female, Bartholin's glands 

 resem])le Cowper's glands closely in histo- 

 logic structure. 



2. Male and Female Prostate Glands 



Male prostate. The prostate is a com- 

 pound tubulo-alveolar gland in which the 

 gross structure is variable and may be (1) 

 disseminate or diffuse, in which the glandu- 

 lar acini remain within the lamina propria 

 around the urethra and do not penetrate 

 the voluntary muscle of the urethra, (2) 

 a type in which the gland forms a '"body," 

 sometimes lobed, outside the urethral 

 muscle, or (3) a combination of both types. 

 A disseminate prostate is found in some 

 marsupials (Fig. 6.1) and edentates, and 

 in sheep, goats, the hippopotamus, and 

 the whale. The bull and boar prostates have 

 a disseminate region as well as a discrete 

 body of the gland. In mammals in which 

 there is a glandular body, there may be a 

 solid, compact prostate as in the dog and 

 man, or several lobes as in rodents (Figs. 

 6.2 and 6.3), lagomorphs (Fig. 6.4), and 

 insectivores. 



Fig. 6.L Male opossum reproductive tract. B, 

 bladder; C, Cowper's glands; D, ductus deferens; E, 

 epididymis; P, penis; Pr, prostate I, II, III sur- 

 rounding the urethra; T, Testis; U, ureter. (Re- 

 drawn from C. R. Moore, Phj'siol. ZooL, 14, 1-45, 

 194L) 



A prostate gland has been found in all 

 mammals that have been studied except 

 monotremes, and is the only accessory gland 

 in carnivores such as the ferret, weasel, dog, 

 and bear, and in cetaceans — whales, dol- 

 phins, and porpoises. Oudemans (1892) con- 

 sidered that monotremes and marsupials 

 lack prostate glands but possess well de- 

 veloped urethral glands. His classification 

 of glands as "urethral" (glands of Littrei 

 or "prostatic" depended on whether the 

 glandular acini remained in the urethral 

 stroma or penetrated the muscle to form a 



