Note the elongated flattened gland lying against the concave surface of the vesicular gland. Find its duct and trace it to the anterior end of the urethra. Find also the pair of small glands (probably the ampullary glands), each of which encircles the ductus deferens near its entrance into the urethra.
The prostate gland comprises two regions. One attaches to the dorsal and lateral surfaces of the proximal end of the urethra, and to the dorsal side of the vesicular gland. The other region consists of two prominent lobes lying ventral to the urinary bladder, to which they are attached. The lobes are also fastened to the adjacent body wall. Dissect away the tough external tunic of connective tissue, and note that both parts of the gland are a mass of tubules. The prostatic secretion in man dilutes and lends bulk to the seminal fluid. It has been suggested that in rodents the secretion assists the locomotion of the sperm cells, and also nourishes them.
The urinary bladder is an oval sac attached to the dorsal surface of the ventral part of the prostate gland. The bladder narrows proximally to the neck, which joins the ductus deferentia to form the urethra. Each ureter, or urinary drainage tube of the kidney, joins the corresponding side of the bladder near the neck. Urine entering the bladder through the ureters, is stored there temporarily, then flows through the neck into the urethra, which conveys it to the outside. The urethra also carries the spermatic fluid during copulation.
The descent of the testis carries the ductus deferens ventral to the ureter. This accounts for the way these tubes loop around each other in the adult.
A mesentery in the sagittal plane connects the bladder and posterior part of the prostate gland with the ventral body wall.
