Lymphatic drainage starts at the septula testis

Clinically, besides vasectomy, induction of

and occurs via the tunica albuginea and the rete

anti-sperm antibodies (ASA) is discussed for

testis. Lymph vessels pass the spermatic cord

urogenital infections, genital trauma, and tes-

and the canalis inguinalis and opens into nodi

ticular tumors as risk factors determining

lymphatici lumbales in direct vicinity to the

fertility.8

abdominal aorta.

Note that blood supply and lymphatic drain-

age are distinct between testis and scrotum. The

Epididymis and Ductus Deferens

paired testicular arteries arise directly from the

abdominal aorta and descend through the ingui-

As has already been mentioned, spermatogene-

nal canal, while the scrotum and the rest of the

sis occurs within the seminiferous epithelium of

external genitalia is supplied by the internal

the seminiferous tubules. Following sperm-

pudendal artery (itself a branch of the internal

iation, spermatozoa pass the rete testis and enter

iliac artery). Lymphatic drainage of the testes

the ductuli efferentes, 8–12 of which connect the

follows the testicular arteries back to the para-

rete testis with the ductus epididymidis.

aortic lymph nodes, while lymph from the scro-

The columnar epithelium of the ductuli effer-

tum drains to the inguinal lymph nodes.

entes is underlined by smooth muscles and con-

Nerves originate from the plexus testicularis,

sists of two cell types: absorptive cells with

which is located within the retroperitoneum

microvilli and cells with kinocilia responsible

where the testicular artery leaves the aorta.

for the transport of still immotile spermatozoa.

Nerves join the testicular artery on its way to the

As the height of these two cell types is variable,

testis and ramify within the tunica albuginea,

the lumen shows a characteristic wavy outline

but do not enter the seminiferous tubules.

(Fig. 4.10).

Therefore, the seminiferous epithelium is devoid

Spermatozoa enter the epididymis via the

of any nerves. Although crushing of testes (e.g.,

head (caput), progress to the body (corpus),

sport) is extremely painful, only little is known

and finally reach the tail (cauda), where they

about afferent nerve fibers ending at around the

are stored. During their passage through the

level of thoracal segment 10 of the spinal cord.

epididymis, spermatozoa undergo maturation

Sensoric innnervation of the scrotum occurs via

to acquire the motility necessary for fertiliz-

the genitofemoralis nerve (ramus genitalis) and

ing an egg. Note that final maturation is com-

the ilioinguinalis nerve. The nervus genitofemo-

pleted within the female reproductive tract

ralis, in addition, is responsible for the motoric

(capacitation).

innervation of the musculus cremaster and the

tunica dartos.

The blood–testis barrier: Due to the presence

of tight junctions between adjacent Sertoli cells,

large molecules cannot pass from the blood into

Epithel of rete testis

the lumen of the seminiferous tubules. While

spermatogonia are located within the basal

compartment (deep to the level of the tight junc-

tions), primary and secondary spermatocytes,

Connective tissue

as well as round and elongated spermatids occur

in the adluminal compartment. The blood–tes-

tis barrier is thought to prevent an auto-immune

reaction, as mature sperm (and their antigens)

arise long after immune tolerance is established

Epithel of ductuli

in infancy. Therefore, as sperm are antigenically

efferentes

different from self-tissue, a male animal can

react immunologically to his own sperm. In fact,

he is capable of making antibodies against them.

Injection of sperm antigens causes inflamma-

tion of the testis (autoimmune orchitis).

Figure 4.10. histology of ductuli efferentes, h&E.

64

Practical Urology: EssEntial PrinciPlEs and PracticE

Smooth muscle

circular layer of smooth muscles between inner

Principal cells

and outer longitudinal layers. The prominent

Stereocilia

muscularis, which makes the ductus deferens

palpable within the spermatic cord (Fig. 4.12),

is covered by an adventitia. During ejaculation,

smooth muscles within the wall of the ductus

Spermatozoa

deferens contract and propel the sperm for-

ward into the urethra. This impulse originates

from abdominal and pelvic sympathetic nora-

drenergic nerves and results in the release of

norepinephrine that subsequently binds to a1A

receptors located on smooth muscles.9

Clinic: Vasectomy is the major operation of

Basal cells

the vas deferens. Nearly 7% of all married cou-

ples choose vasectomy as their form of birth

Figure 4.11. histology of epididymis, h&E.

control.10 The ductus deferens is part of the

spermatic cord or funiculus spermaticus. This

structure is covered by an external spermatic

The ductus epididymidis is about 6 m long

fascia (a continuation of the fascia from the

and is lined by a tall columnar epithelium, which

external oblique muscle), the cremasteric fas-

is underlined by smooth muscles and consists of

cia (a continuation of the fascia from the inter-

basal cells and principal cells with nonmotile

nal oblique muscle) and an internal spermatic

stereocilia. From caput to cauda, the height of

fascia (a continuation of the transversalis fas-

the epithelium decreases, while the diameter of

cia). It contains the ductus deferens, arteries

the ductus and the lumen increases (Fig. 4.11).

(testicular artery, deferential artery, and cre-

The ductus deferens or vasa deferentia –

masteric artery), the pampiniform plexus, lym-

each about 30 cm long – connect right and left

phatic vessels, nerves (genitofemoralis nerve

epididymis to the ejaculatory ducts. The duc-

and sympathetic nerve), and the processus

tus deferens can be divided into pars funiculi

vaginalis.

spermatici, pars inguinalis, pars pelvina, amp-

The spermatic cord is sensitive to torsion.

ulla ductus deferentis, and ductus ejaculato-

The most common age at which testicular tor-

rius, which open into the urethra (colliculus

sion occurs is during puberty and the second

seminalis).

most common is in the newborn. As a conse-

The mucosa forms longitudinal folds and is

quence, testicles may rotate within its sac and

lined by a columnar epithelium. The muscularis

may kick off its own blood supply resulting in

is up to 1.5 mm thick and consists of a thick

irreversible damage to the testicles within hours.

Stereocilia

Columnar cells

Basal cells

Longitudinal

smooth muscle

Circular

smooth muscle

Longitudinal

smooth muscle

Mucosa

Figure 4.12. histology of vas deferens,

h&E.