ACCESSORY MAMMALIAN REPRODUCTIVE GLANDS 



367 



embryonically from the mesonephric or 

 Wolffian duct (ductus deferens) i.e., the 

 ampullary glands (glandula vasis defer- 

 entis) and seminal vesicles or vesicular 

 glands, and those deriving from the uro- 

 genital sinus or urethra, namely the pros- 

 tate and bulbo-urethral or Cowper's glands 

 (see chapter by Burns). The anatomic re- 

 lationships established in the fetus are re- 

 tained to a considerable degree postnatally 

 so that the ampullary glands and seminal 

 vesicles are associated with the ducti defer- 

 entes. However, in some mammals the semi- 

 nal vesicles empty into the pelvic urethra 

 close to the openings of the deferent ducts 

 but separate from them; no ejaculatory 

 ducts are present. The prostatic and bulbo- 

 urethral glands are associated with the 

 proximal and distal urethra, respectively. 

 The secretion of the prostate is discharged, 

 in most cases, through multiple ducts that 

 join the prostatic urethra at the level of 

 the colliculus seminalis. The ducts of the 

 bulbo-urethral glands drain into the urethra 

 in the region of the urethral bulb. 



In addition to these accessory reproduc- 

 tive glands, there are small mucus-secreting 

 glands (of Littre) opening into the urethra 

 along its length, and preputial glands 

 (which are modified sebaceous glands) 

 emi)tying their secretion on the prepuce. 



In many female mammals, homologues of 

 the male prostate and bulbo-urethral glands 

 develop in the fetus. These glands may ret- 

 rogress prenatally, remain vestigial, or de- 

 velop postnatally and become functionally 

 active. These homologues are the female 

 prostate glands (para-urethral glands of 

 Skene) and the bulbovestibular (major 

 vestibular or Bartholin's glands). In addi- 

 tion, there are urethral glands (minor ves- 

 tibular) which are homologous with the 

 male urethral glands of Littre, and female 

 preputial or clitoridal glands corresponding 

 to the male preputials. The major vestibu- 

 lar, when present, and the minor vestibular 

 and clitoridal glands are functional in many 

 mature females. In a few cases, well devel- 

 oped prostate glands which are actively se- 

 cretory have been found in females of four 

 mammalian orders. 



B. GENERAL CHARACTERISTICS 



The male accessory reproductive glands 

 of higher mammals have many character- 

 istics in common. Typically, all possess (1) 

 a secretory epithelium which is enormously 

 increased in effective secretory area by vil- 

 lous infoldings, or by a compound tubulo- 

 alveolar structure, (2) an underlying layer 

 of connective tissue (the lamina propria) 

 and (3) smooth muscle fibers. It is now well 

 established that the secretory activity of the 

 epithelial cells is normally under the control 

 of testicular hormones. The secretions pass 

 from the cells into the lumina of the glandu- 

 lar alveoli where they are usually stored 

 until ejaculation. 



The sensory innervation includes various 

 types of sensory nerve endings in the con- 

 nective tissue, and free nerve endings in 

 the epithelium. The autonomic innervation 

 is parasympathetic (nervi erigentes) and 

 sympathetic (hypogastric nerve) from the 

 pelvic plexus. If the plexus is resected or 

 the sympathetic chain above is interrupted, 

 there is no reflex ejection of the glandular 

 secretions. When the hypogastric nerve is 

 stimulated, peristaltic waves of contraction 

 occur in the ductus deferens, and there is 

 contraction in the seminal vesicles and pros- 

 tate which partially empties the stored se- 

 cretion from the lumina of these glands. 

 Stimulation of the parasympathetic system 

 or the administration of pilocarpine results 

 in an increased output of prostatic secre- 

 tion. 



There are marked dissimilarities in gross 

 structure, character of the epithelia, and the 

 chemical nature of the secretions in the 

 various glands — ^prostates, seminal vesicles, 

 bulbo-urethral, and ampullary (Mann, 

 19o4a). There are also differences in struc- 

 ture and function between homologous 

 glands in related forms. The nomenclature 

 that was applied to the glands in early de- 

 scriptive studies was often based on ana- 

 tomic relationships and gross morphologic 

 structure in adults. This resulted in some 

 confusion in classification, but most of the 

 disputed points have been clarified and 

 some of the homologies have been estab- 

 lished by embryologic study. The extensive 

 studies of INIann (1954a) show clearly that 



