The male reproductive system

Question 1

Describe the seminiferous tubules of the testes

Answer 1

• Spaghetti-like
• Coiled together
• Site of spermatogenesis
• Large overall length

Question 2

Describe the capsule of the penis

Answer 2

• Named the tunica albuginea
• Surrounds seminiferous tubules
• Collagen fibres arranged at right angles to each other.
• Very dense and strong and gives penis its cylindrical shape.
• Rupture of the tunica albuginea results in a fractured penis.

Question 3

What is the tunica vaginalis?

Answer 3

• Serous membrane
• Made up of parietal layer, cavity, visceral layer
• Derived from the embryonic vaginal process - an outpouching of the parietal peritoneum, which follows the testes during descent and then encloses them.

Question 4

What is the head of epididymis?

Answer 4

• A sperm nursery - sperm are stored and mature here
• Sperm travel here from the seminiferous tubules

Question 5

What is a hydrocoele?

Answer 5

• When the tunica vaginalis fills with fluid

Question 6

What is the function of the sertoli cells?

Answer 6

• Found around the lumen of the seminiferous tubules
• Remove excess cytoplasm of spermatozoa so that sperm are streamlined and can swim faster.

Question 7

What is the function of the Leydig cells?

Answer 7

• Creates space between seminiferous tubules
• Contain lots of smooth ER for lots of androgen synthesis.

Question 8

At what temperature does spermatogenesis occur in humans?

Answer 8

• 35oC

Question 9

Where do the testicular veins drain?

Answer 9

• Right testicular vein drains into inferior vena cava
• Left testicular vein drains into left renal vein

Question 10

What is the pampiniform plexus?

Answer 10

• The testicular veins form a network that wraps around the testicular artery.
• The veins carry cool blood from the scrotum back into the body.
• This creates a counter-current flow that allows blood in the artery to cool down.
• The arterial blood is now at optimum temperature for spermatogenesis.

Question 11

What supplies the testicular arteries with blood?

Answer 11

• Abdominal aorta

Question 12

Outline the lymphatic drainage of the testes

Answer 12

• Testes drain into paraaortic lymph nodes that surround the aorta
• Skin of scrotum drains into inguinal lymph nodes.

Question 13

Why is torsion a surgical emergency?

Answer 13

• Happens when testis twists around its axis
• Venous drainage is occluded, causing swelling.
• This swelling then occludes arteries supplying testis with blood.
• Testis can die
• This threatens fertility

Question 14

What congenital defect results in testicular torsion?

Answer 14

• In a normal testicle, the tunica vaginalis is partially attached to the scrotum, preventing twisting from happening.
• Absence of this attachment allows torsion to occur.
• If testis is fully invaginated within tunica vaginalis, it can twist but not untwist itself back to its original position.

Question 15

What is the name of the defect where the testicle is too deeply invaginated in the tunica vaginalis?

Answer 15

• Bell-clapper deformity

Question 16

Can testicles swap sides?

Answer 16

No - this is prevented by a septum

Question 17

What is the dartos fascia?

Answer 17

• A thin muscle that extends up between the testes.
• Sits just beneath the skin
• Causes wrinkling of scrotal skin

Question 18

Outline the descension of the testes during development

Answer 18

• Testis starts off high in abdominal wall
• Descent guided by gubernaculum (a string-like structure)
• No hole is punched - the testis forces out the layers of abdominal wall muscles like stretching clingfilm.
• Layers of abdominal wall muscle become spermatic fascia
• Testis forms inguinal canal in its wake as it passes through the abdominal wall.

Question 19

What are the 3 fascial layers of the spermatic cord?

Answer 19

1. Internal spermatic fascia (derived from transversalis fascia)
2. Cremasteric fascia (derived from internal obliques)
3. External spermatic fascia (derived from external obliques)

Question 20

What are the 3 arteries/veins of the spermatic cord?

Answer 20

1. Testicular artery/vein
2. Vein from the vas
3. Cremasteric vein

Question 21

What are the 3 nerves of the spermatic cord?

Answer 21

1. Genital branch of the genitofemoral nerve (motor to cremaster muscle)
2. Autonomics (sympathetics to vas)
3. Ilioinguinal nerve (sensory to part of external genitals and upper inner thigh).

Question 22

What are the 3 other parts of the spermatic cord?

Answer 22

1. Vas deferens
2. Lymphatics
3. Patent processus vaginalis (not normal, usually obliterates during development)

Question 23

What do we mean by water under the bridge in terms of anatomy?

Answer 23

• The vas deferens runs over the ureter

Question 24

What are the accessory glands of the male reproductive system?

Answer 24

• Seminal vesicles - produce 65% of ejaculate
• Prostate - produces 25% of ejaculate

-Bulbourethral glands - only produce ~ 1% of ejaculate

Question 25

Why is ejaculate alkaline?

Answer 25

• Because the vagina is very acidic

Question 26

Which part of the prostate tends to be affected by BPH?

Answer 26

• The transitional (central) zone
• Prostate cancers tend to affect peripheral zone

Question 27

What are the functions of the penis?

Answer 27

• Expulsion of urine via urethra
• Deposition of sperm in female genital tract

Question 28

Describe the structure of the penis

Answer 28

• Corpus cavernosum x2 anchors penis to pubic arch of pelvis.
• Corpus spongiosum x1 carries urethra

Question 29

Why does the corpus spongiosum not get too turgid with blood during erection?

Answer 29

• Otherwise the urethra would become obstructed.

Question 30

How does an erection occur?

Answer 30

• Vasodilation in penile arterioles and compression of veins results in erection.
• Vasodilation is initiated by parasympathetic stimulation
• Erection is terminated by vasoconstriction (sympathetic)

Question 31

What vessel supplies the penis with blood?

Answer 31

• Internal iliac artery