Lecture 24: Male Reproductive Tract Flashcards
Tell me about the testicular decent
- 7 months: testosterone stimulates descent of testes from pelvis to scrotum.
- Descent guided by gubernaculum extending from testis to floor of scrotal sac.
- Drags supplying blood vessels and nerves along behind => spermatic cord
Tell me about the embryonic development
Slide 3
- the proximal mesonephric duct becomes the epididymis
- remainder of mesonephric duct becomes the ductus (vas) deferens and ejaculatory duct.
- Fetal testes produce Mullerian-inhibiting factor (MIF) which suppresses development of Mullerian (future female) ducts.
- 8th week: Leydig cells secreting testosterone.
- Testosterone induces masculine differentiation of mesonephric ducts and external genitalia.
What is the blood supply and the venous drainage of the penis?
• Blood supply: internal pudendal arteries, external pudendal arteries, dorsal arteries, deep arteries, arteries of the bulb
• Venous drainage: deep and
superficial dorsal veins.
Check out image on slide 14
Describe to me the scrotum “pouch”.
Tell me the layers of the scrotum and covering of testis
Layers of scrotum and coverings of testis: • Skin • Dartos fascia and dartos muscle • External spermatic fascia • Cremaster muscle • Cremasteric fascia • Internal spermatic fascia • Tunica vaginalis (parietal) • Tunica vaginalis (visceral) • Tunica albuginea (innermost layer covering testis) Slide 16
Tell me about the layers surrounding the testis
• Suspended in scrotum by spermatic cord.
• Tunica vaginalis: visceral & parietal layers of peritoneum.
• Tunica albuginea: “white coat” tough fibrous outer surface of testis.
Slide 17 and 18
Tunica albuginea forms septa inside testis.
Mature spermatozoa move from seminiferous tubules through rete testis and efferent ductules to be stored in the epididymis awaiting ejaculation. (Slide 20)
What is the blood supply of the testes?
Arterial supply:
• Testicular arteries
• Artery of ductus deferens
• Venous drainage:
• Pampiniform plexus ➡Right
testicular vein ➡ IVC
• Pampiniform plexus ➡Left testicular vein ➡ Left renal vein.
What lies in the spermatic cord?
What are the 3 coverings of the spermatic cord?
Ductus deferens • Testicular artery • Artery of ductus deferens • Cremasteric artery • Pampiniform plexus • Sympathetic nerve fibres • Genitofemoral nerve • Lymphatic vessels
Three coverings:
• Internal spermatic fascia (derived from
transversalis fascia).
• Cremasteric fascia (derived from fascia of internal obliques and contains loops of cremaster muscle).
• External spermatic fascia (derived from external oblique aponeurosis and fascia)
• Cremaster muscle innervated by genitofemoral nerves (L1-L2).
The spermatic cord
-Begins at deep inguinal ring lateral to inferior epigastric vessels.
• Exits at superficial inguinal ring.
• Ends in scrotum at posterior pole of testis.
Epididymis
Posterior surface of testis. • Head. • Body. • Tail. • Efferent ductules of testis transport newly developed sperm from rete testis to epididymis. Slide 30
Tell me about the ductus (vas) deferens “carrying away”
- Continuation of duct from tail of epididymis.
- Thick muscular walls, minute lumen.
- Primary component of spermatic cord.
- Crosses over external iliac vessels and enters pelvis.
- Ends by joining duct of seminal vesicles to form ejaculatory duct.
The seminal vesicle slide 33
Posterior to bladder. • Anterior to rectum. • Superior to prostate. • Inferior to rectovesical pouch. • Secrete thick alkaline fluid with fructose and coagulating agent that mixes with sperm as they enter the ejaculatory duct and urethra.
Ejaculatory ducts
Formed by union of ducts of seminal vesicles with ductus deferens.
• 2.5cm long.
• Arise near neck of bladder.
• Pass anteroinferiorly through posterior prostate.
• Opens into prostatic utricle.
• Prostatic secretions join seminal fluid in prostatic urethra AFTER ejaculatory ducts have terminated.
Tell me about the prostate gland?
Largest accessory gland of male reproductive tract.
• Surrounds prostatic urethra.
• Secretion = 1/3 of semen volume; milky, slightly acidic contains citrate and enzymes that activates sperm.
• Enters prostatic urethra via ducts when prostatic smooth muscle contracts during ejaculation.
Slide 35
Tell me about a prostate examination?
Benign hypertrophy of the prostate (BHP) is common after middle age.
• Enlarged prostate projects into urinary bladder and distorts prostatic urethra impeding urination.
• TURP = Transurethral resection of prostate.
Slide 36
Describe to me the bulbourethral gland and its function
Also called Cowper’s Gland.
• Pea-sized glands.
• Posterolateral to the intermediate part of urethra.
• Embedded in external urethral sphincter.
• Open through tiny holes into proximal part of the spongy urethra in bulb of penis.
• Under parasympathetic stimulation: Secrete clear mucous-like fluid during sexual arousal which neutralises traces of acidic urine in the
urethra and lubricates glans penis.
What are the 4 parts of the male urethra?
- ntramural (pre-prostatic) part [0.5-1.5 cm]
- Prostatic part [3-4 cm]
- Intermediate (membranous) part [1-1.5 cm]
- Spongy urethra [15cm]
Slide 38
