Session 3 Anatomy of male repro system

• Internal urethral sphincter ?

  • Function: urinary continence
  • At the junction of the bladder and urethra
  • Smooth muscle, continuous with detrusor muscle
  • Innervation: under autonomic control
• Three parts of urethra?

  • Prostatic (widest)
  • Membranous (narrowest)
  • Spongy
• external urethral sphincter: voluntary control of micturition.
• Dilates to form navicular fossa at glans - spongy urethra (penile)
• male urethral catheterisation - used to treat urinary retention/ inability to void bladder
• Components of testes?

  Seminiferous tubules, rete testes, epididymis, efferent ductules, vas deferens, tunica albuginea and vaginalis
• Seminiferous tubules Function ?

  • Spermatogenesis
  • Testosterone production in interstitial tissue
• Seminiferous Tubules: site of spermatogenesis
• Cells of seminiferous tubules?

  • Spermatogonium - Undifferentiated male germ cells. Undergo mitosis and then meiosis to form spermatozoa.
  • Sertoli cells - ‘Nurse cells’. Secretion e.g. androgen binding protein to increased local testosterone concentration. Structure incl blood-testis barrier.
  • Leydig cells - Produce testosterone in response to LH.
• Rete testis Function?

  mix sperm and modify fluid
• Epididymis Function?

  • maturation of sperm, including sperm gaining motility
  • Storage of sperm in tail until ejaculation
• Ductus/ vas deferens Function?

  transports sperm from epididymis to ejaculatory ducts in pelvis
• Tunica albuginea: provides support and structure.

  Tunica vaginalis: allows some testicular mobility.
• Hydrocele: Fluid collection between visceral and parietal layers of tunica vaginalis.
• What are the contents of the spermatic cord?

  • Testis - Testicular artery, Pampiniform plexus
  • Vas deferens - Artery to vas deferens
  • Cremaster muscle - Cremasteric artery and vein, Genital branch of genitofemoral nerve
  • Other structures: Lymphatic, Autonomic nerves, Ilioinguinal nerve
• Cremaster muscle Function?

  raises and lowers testes to regulate temperature (alongside dartos) + protects testes.
• 3 fascial coverings?

  • Outer: external spermatic fascia (from external oblique aponeurosis)
  • Cremaster muscle and fascia (from internal oblique)
  • Inner: internal spermatic fascia (from transversalis fascia)
• • Right testicular vein > drains to IVC
  • Left testicular vein > drains to left renal vein.
• Layers of scrotum?

  • Skin
  • Superficial fascia containing dartos muscle (helps regulate temp)
• The spermatic cord and its contents twists, compromising blood flow to the testicle. Usually in the tunica vaginalis. - Testicular torsion
• Structure of ductus deferens?

  • Outer layer: connective tissue
  • Middle layer: smooth muscle– contracts to propel sperm towards ejaculatory duct during ejaculation
  • Inner layer: pseudostratified columnar epithelium with cilia
• The Accessory Male Sex Glands?

  1. Seminal Vesicles
  2. Prostate gland
  3. Bulbourethral Glands
  4. Function: form the bulk of the seminal fluid (semen)
• Function of prostate gland?

  secrete proteolytic enzymes to break down clotting factors in semen (via prostatic ducts).
• Elevation of the urothelium that serves as a landmark for the opening of the ejaculatory ducts - colliculus seminalis
• Label zones of prostate gland

  A) Central zone

  B) Peripheral zone

  C) Transitional zone

  D) Fibromuscular stroma

  
• Clinical relevance of transitional zone of prostate gland?

  benign prostatic hyperplasia - Hyperplasia of prostate tissue, most commonly transitional zone. Results in lower urinary tract symptoms.
• Clinical relevance of peripheral zone of prostate gland?

  prostate cancer - Peripheral zone is most common site. Often will not present with LUTS.
• Duct of seminal vesicle + ductus deferens = ejaculatory duct (empties into prostatic urethra)
• Seminal vesicles?

  • Function: produce alkaline seminal fluid which forms 70-80% of ejaculate volume
  • Development: develops as outgrowth of ductus deferens.
• Bulbouretheral glands?

  • 2 pea sized glands (Cowper’s glands) sit posterolaterally to the membranous urethra
  • Secrete a pre-ejaculate into spongy urethra.
  • Helps to neutralise residual acidity in the male urethra
  • Lubrication for the urethra and the tip of the penis.
  • Expels any residue of urine, dead cells or mucous through the urethral meatus - clean and lubricated pathway for ejaculation.
• Parts of penis?

  • Root- attaches to abdominal wall
  • Body/shaft
  • Glans
• Corpus cavernosum > erectile tissue

  Corpus spongiosum > surrounds urethra
• Erection = parasympathetic

  Ejaculation = sympathetic
• Blood supply to penis?

  • Internal pudendal artery (from internal iliac)
  • Deep & dorsal penile arteries (for erection)
• Venous Drainage for penis?

  • Dorsal Veins (superficial & deep) drain to prostatic venous plexus.
• Label the penis structures

  A) Superficial dorsal vein

  B) Deep dorsal vein

  C) Corpus cavernosum

  D) urethra

  E) corpus spongiosum

  F) dorsal artery

  G) Deep artery

  
• The deep (cavernous artery) gives off helicine artery branches. Helicine arteries supply sinusoids and trabecular tissues.
• Erection is a NEUROVASCULAR PROCESS

  • Sexual arousal or mechanical stimulus
  • Parasympathetic activation (S2-S4) ‘Point’
  • Specifically: pelvic splanchnic nerves > inferior hypogastric plexus > prostatic plexus > cavernous nerves
  • Cavernous nerves release nitric oxide
  • Relax smooth muscle of helicine arteries
  • Vasodilate + fill sinusoids with blood
  • Increased pressure in corpus cavenosa decreases venous return ‘veno-occlusive’ mechanism .
• Ejaculation has two phases: Emission > Ejaculation
• Emission

  • Under sympathetic control (L1 and 2) > shoots
  • Internal urethral sphincter closes
  • Peristalsis of ductus deferens and seminal vesicles
  • Prostate smooth muscle contracts
  • Ejaculate squeezed into the penile bulb