322 AN INTRODUCTION TO ZOOLOGY 



the epididymis, in which three regions may be distinguished. The 

 first is a rounded mass of this tissue, the caput epididymis, closely 

 adherent to the anterior end of the testes near the attachment of 

 the spermatic cord. The second is a narrow band passing along the 

 medial side of the testis, and the third is a larger, somewhat conical 

 mass, the cauda epididymis, attached to the posterior end of the 

 testis. It is the cauda that is attached to the wall of the scrotal sac 

 by means of a short strand of connective tissue, the gubernaculum. 



Developmentally we find that the epididymis is the persistent 

 highly modified remains of the mesonephros of the embryo, and its 

 tubules grow into the testis constituting the vasa efferentia. The 

 vas deferens is then the old mesonephric duct. The vasa deferentia 

 arise from the cauda epididymis, pass through the inguinal canal into 

 the abdominal cavity to a position on the outside of the ureters. 

 They loop over the ureters ventrally and then run back on the dorsal 

 side of the bladder to open into its neck below the ureters. From 

 this point on there is one common duct for both the urinary and 

 genital products, and it is termed the urethra. A median, short 

 thick-walled sac, the uterus masculinus, opens into the urogenital 

 canal, as the urethra may be called, a little lower down, and the 

 canal then passes on ventral to the end of the rectum, and imme- 

 diately dorsal of the pelvic symphysis to be continued outside the 

 body in the penis. The penis or male copulatory organ is a short 

 rod of tissue projecting from the ventral end of the perineum, but 

 it is not conspicuous, since its free end is enclosed in a fold of skin, 

 termed the prepuce. The posterior wall of the penis is formed of a 

 very characteristic vascular tissue, the corpus cavernosum, while its 

 ventral wall contains two closely apposed rods of firmer tissue, the 

 corpora spongiosa, which diverge in the substance of the abdominal 

 wall and are attached one to each ischium. The dorsal wall of the 

 urethra just below the uterus masculinus bears a gland, the prostate, 

 composed of four or five lobes which open into the urogenital canal 

 on each side of a median papilla, the verumontanum, lying just below 

 the aperture of the uterus. Still lower down are a pair of small 

 ovoid bodies, Cowper's glands, one on each side of the dorsal surface 

 of the urethra. 



The rectum is a muscular thin-walled tube lying close -to the 

 urethra, but opening to the exterior by an entirely separate aperture, 

 the anus. On its dorso-lateral walls it bears a pair of long, pale 

 yellow bands of tissue, the rectal glands. On each side between 

 rectum and urethra is a small perineal gland of a dark colour which 

 opens on to a shallow depression, the perineal sac on the perineal area. 

 It produces a secretion which is responsible for the characteristic 

 smell of the rabbit. 



