The male reproductive system Flashcards
Describe the seminiferous tubules of the testes
- Spaghetti-like
- Coiled together
- Site of spermatogenesis
- Large overall length
Describe the capsule of the penis
- 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.
What is the tunica vaginalis?
- 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.
What is the head of epididymis?
- A sperm nursery - sperm are stored and mature here
- Sperm travel here from the seminiferous tubules
What is a hydrocoele?
- When the tunica vaginalis fills with fluid
What is the function of the sertoli cells?
- Found around the lumen of the seminiferous tubules
- Remove excess cytoplasm of spermatozoa so that sperm are streamlined and can swim faster.
What is the function of the Leydig cells?
- Creates space between seminiferous tubules
- Contain lots of smooth ER for lots of androgen synthesis.
At what temperature does spermatogenesis occur in humans?
- 35oC
Where do the testicular veins drain?
- Right testicular vein drains into inferior vena cava
- Left testicular vein drains into left renal vein
What is the pampiniform plexus?
- 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.
What supplies the testicular arteries with blood?
- Abdominal aorta
Outline the lymphatic drainage of the testes
- Testes drain into paraaortic lymph nodes that surround the aorta
- Skin of scrotum drains into inguinal lymph nodes.
Why is torsion a surgical emergency?
- 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
What congenital defect results in testicular torsion?
- 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.
What is the name of the defect where the testicle is too deeply invaginated in the tunica vaginalis?
- Bell-clapper deformity
Can testicles swap sides?
No - this is prevented by a septum
What is the dartos fascia?
- A thin muscle that extends up between the testes.
- Sits just beneath the skin
- Causes wrinkling of scrotal skin
Outline the descension of the testes during development
- 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.
What are the 3 fascial layers of the spermatic cord?
- Internal spermatic fascia (derived from transversalis fascia)
- Cremasteric fascia (derived from internal obliques)
- External spermatic fascia (derived from external obliques)
What are the 3 arteries/veins of the spermatic cord?
- Testicular artery/vein
- Vein from the vas
- Cremasteric vein
What are the 3 nerves of the spermatic cord?
- Genital branch of the genitofemoral nerve (motor to cremaster muscle)
- Autonomics (sympathetics to vas)
- Ilioinguinal nerve (sensory to part of external genitals and upper inner thigh).
What are the 3 other parts of the spermatic cord?
- Vas deferens
- Lymphatics
- Patent processus vaginalis (not normal, usually obliterates during development)
What do we mean by water under the bridge in terms of anatomy?
- The vas deferens runs over the ureter
What are the accessory glands of the male reproductive system?
- Seminal vesicles - produce 65% of ejaculate
- Prostate - produces 25% of ejaculate
-Bulbourethral glands - only produce ~ 1% of ejaculate
Why is ejaculate alkaline?
- Because the vagina is very acidic
Which part of the prostate tends to be affected by BPH?
- The transitional (central) zone
- Prostate cancers tend to affect peripheral zone
What are the functions of the penis?
- Expulsion of urine via urethra
- Deposition of sperm in female genital tract
Describe the structure of the penis
- Corpus cavernosum x2 anchors penis to pubic arch of pelvis.
- Corpus spongiosum x1 carries urethra
Why does the corpus spongiosum not get too turgid with blood during erection?
- Otherwise the urethra would become obstructed.
How does an erection occur?
- Vasodilation in penile arterioles and compression of veins results in erection.
- Vasodilation is initiated by parasympathetic stimulation
- Erection is terminated by vasoconstriction (sympathetic)
What vessel supplies the penis with blood?
- Internal iliac artery
