and short (nonciliated). Also shown are the seminiferous tubules (C)and the
mediastinum testis containing the rete testis (A).Sperm leave the seminifer-
ous tubules through short tubuli recti into the straight tubules of the rete
testis, which subsequently drain into the efferent ductules. For the vas defer-
ens, see answer to question 238.
238.The answer is d.(Young, p 336. Junqueira, pp 429–430.)The organ
shown in the figure is the vas deferens (ductus deferens). The vas deferens
conducts sperm from the epididymis to the urethra. The thick muscular
wall is unique in the presence of an inner longitudinal, a middle circular,
and an outer longitudinal layer of smooth muscle. The ureter has two thin
layers of muscle: inner longitudinal and outer circular (answer c).The
male and female urethra contain extensive vascular channels (answers a
and b).The epididymis consists of a connective tissue stroma and stores
sperm, resorbs fluid, and produces sperm maturation factors (answer e).
239.The answer is b.(Young, pp 339–340. Junqueira, p 433.)The pho-
tomicrograph shows the histology of the male (penile) urethra. It possesses
a primarily pseudostratified columnar type of epithelium. The glands of
Littré that produce mucus are also observed in the section. The thick-
walled arteries of the penile and cavernous sinuses of penile erectile tissue
are also a distinguishing feature of this organ. Helicine arteries supply the
sinuses. Action of the parasympathetic nervous system mediates the dila-
tion of these vessels during erection.
240.The answer is c.(Young, pp 337–339. Junqueira, pp 429–431. Kasper,
pp 1025–1033.)The photomicrograph is from the prostate. Seventy percent
of carcinomas of the prostate arise from the main (external gland), also
known as the outer (peripheral) glands (answer b).The prostate consists of
three parts: (1) a small mucosal (inner periurethral) gland, (2) a transition
zone that consists of a submucosal (outer periurethral) gland, and (3) a
peripheral portion known as the main, or external, gland. Because of the
peripheral location, most prostatic carcinomas (primarily adenocarcinomas)
remain undiagnosed until the later symptoms of back pain or blockage of the
urethra are detected. Digital rectal examination can identify some tumors
earlier. Benign prostatic hypertrophy, also known as benign nodular hyper-
plasia, occurs in the mucosal and submucosal glands, which are rarely sites
of carcinoma. Benign hyperplasia causes urethral obstruction in its early
Reproductive Systems Answers 375