Male Reproductive Viscera

Christopher Ramnanan, Ph.D.cramnana@uottawa.ca

-Describe the embryological origins of the male reproductive system

-Identify the anatomical structures, blood supply, and innervation associated with the male reproductive system

-Identify the histological features of the testis, epididymis, prostate, seminal vesicles and penis

This talk will focus on anatomy; embryology and histology covered thoroughly in Dr. Savory and Dr. El-Bialy’s respective presentations

Male Reproductive

System

Epididymis

Testes

Seminal Vesicle

Prostate

Ductus Deferens

Penis

Testes originate on posterior body wall (proximal to kidneys) and descend during development in retroperitoneal position.

Posterior wall of parietal peritoneum

Testes

Ductus deferens

Gubernaculum testis (caudal portion of genital ligament)

Processus vaginalis: outpouching of peritoneum

7th week

In the last trimester, the testes descend through the inguinal canal in part due to the relative shortening of the gubernaculum.

7th month

Gubernaculum testis

Note: the processus vaginalis precedes the testes; the testes pick up layers derived from anterior abdominal wall

9th month

Testes descend to their final position in 9th month (97%). The communication b/w the processus vaginalis and the peritoneal cavity becomes obliterated, leaving behind the tunica vaginalis.

Gubernaculum testis (scrotal ligament)

Clinical NotesOne or both testes fail to descend, a condition termed cryptorchidism (resulting in ectopic testis, and increased risk of infertility and testicular cancer).

The tunica vaginalis can be associated with (A) testicular hydrocele. A patent process vaginalis increases risk of (B-C) indirect inguinal hernias. Risk of this type of herniation is greater in males and is routinely tested for (D; ‘turn your head and cough’).

A

B C D

Inguinal CanalAnatomical passage between the deep and superficial inguinal rings for:

-Spermatic cord in males -Round ligament of uterus in females

-Ilioinguinal nerve and Genital br. of genitofemoral n. in both sexes

1. External Oblique

2. Int. Oblique

3. Transversalis Muscle and Fascia4. Peritoneum

Note: Layers of Abdominal Wall will give rise to coverings of Spermatic cord/Testis

Epididymis: 1. Head2. Body3. Tail

1

2

3Lobules (containing sperm-producing seminiferous tubules)

Tunica Albuginea (fibrous coat; gives rise to septa)

Ductus deferens

Ductus (vas) deferens and Testis

Ductus (vas) Deferens and Seminal VesiclesDuctus deferens enters body via inguinal canal, moves medially and ends by joining the duct of the seminal vesicle to form the ejaculatory duct

Seminal Vesicle and its duct

Prostatic Urethra (termination of Ejac. Duct)

Ductus Deferens

Ejaculatory Duct

Prostatic Urethra and openings of prostatic ducts (many)

Ductus Deferens and its Ampulla

Ejaculatory Duct (most of duct runs within prostate)

Posterior View Anterior View (Frontal Section)

Seminal Vesicle

Ejac Ducts open at margins of seminal colliculus (bump) near the prostatic utricle (blind pouch; derived from parames. ducts)

Membr. Urethra

Spongy Urethra

Opening of Ejac. Duct (2)

Visible in Lab Conceptual View

Prostate3 major anatomical lobes in adult (5 in fetus):

Anterior lobe (isthmus): anterior to urethra

Two lateral lobes (posterior to urethra; adjacent to rectum; separated from each other and from isthmus by median sulcus; can be palpated via rectal exam)

Prostate3 clinically-described zones in adult:

Peripheral Zone: ~70% of volume; typical site of cancer

Central Zone: 25% of volume; surrounds ejaculatory ducts

Periurethral transitional zone: 5% of gland; surrounds urethra; typical site of B.P.H.

Peripheral ZoneCentral Zone

Periurethral Transitional Zone

External Genitalia

Homology

Scrotum

Body (Shaft) of Penis

Prepuce

Glans Penis

Labia majora

Body of Clitoris

Prepuce

Glans of Clitoris

Labia minoraRaphe of penis

Male Erectile Bodies

-Crura and bulb of penis are homologous to crura of clitoris and bulb of vestibule in females; crura and bulb erectile tissue covered by perineal muscles (perineum anatomy on Nov. 11th)-Spongy urethra is conveyed in corpus spongiosum

View of Superficial Perineal Pouch MusclesMale Female

-The bulbospongiosus muscles are fused (midline raphe of penis) in males but are separate in females; in both sexes, associated with bulb erectile body-The ischiocavernosus muscles attach to ischiopubic rami and are associated with crura erectile bodies in both sexes-Perineal body allows for support and attachment-Muscles generally more prominent in males (bulbospongiosus and ischiocavernosus both aid in maintaining erection; Bulbospongiosus also functions in expelling semen and urine

-Described in anatomical position as being in the erect state-Root: muscles+erectile bodies and attached; Body: only erectile tissue and ‘free’-Spongy urethra is conveyed in corpus spongiosum-Key neurovasculature (dorsal nerve, dorsal artery, deep artery, deep dorsal vein) derived from pudendal n. and internal pudendal a/v (perineum anatomy lab, Nov 12th)

Sympathetic (S; shoot) supply:Descending with testicular arteries or via hypogastric plexuses

Parasympathetic (P, point) supply:From S2-S4; traveling via pelvic splanchnic nerves pelvic plexus (prostatic plexus) cavernous nerves reach erectile tissue

Somatic Innervation (Voluntary Motor to Perineal Muscles/Touch Sensation to Penis/Scrotum): Pudendal N. (S2-S4)

Note: Pelvic Pain Line

Male Reprod. Viscera Innervation

Visceral Pain Lines

Heart (CardiopulmonarySplanchnic Nn., T1- 6)

Thoracic Pain Line: ~plane of sternal angle

Pelvic Pain Line: ~ plane of lower extent of peritoneum

Note: TESTES

Male Reprod. Viscera VascularizationTesticular arteries and veins (pampiniform venous plexus) are visible, descending from abdomen Note: veins are asymmetrical; relationship to ureter; ‘Nutcracker’ effect

Male Reprod. Viscera Vascularization

Blood supply of other viscera (seminal vesicles, prostate, ductus deferens) not discernable in gross lab, but derived from internal iliac artery, drain to internal iliac veinNote: prostatic arteries from nearby arteries (middle rectal, inferior vesicle); prostatic venous plexus in males can communicate with vertebral veins

Blood supply of scrotum, penis, perineal muscles derived from internal pudendal artery

Internal pudendal artery

Male Reprod. Viscera Lymphatics

-Deep structures drain to back body wall following lymph nodes associated with arteries (gonadal, internal iliac) to reach chyle cistern-Superficial structures (scrotum, skin of penis) drains superficially to superficial inguinal lymph nodes (not shown)Clinical Note: Prostatic venous/lymphatic plexus communicates with vertebral plexuses; common site of prostatic cancer metastasis is to vertebral column

Superficial Ing. l. n.

NOTE: TestesPara-aortic Lymph nodes