Male reproductive organs

  1. Embryology of male reproductive system
    • Retroperitoneal
    • 7-8 gestational mo, testes descend thru inguinal canal
    • Lymph drainage of testes goes into para-aortic lymph nodes in abdomen
  2. Layers of the testis
    • Scrotum (skin)
    • External spermatic fascia: extension of external oblique fascia
    • Cremasteric fascia: extension of internal oblique fascia
    • Internal spermatic fascia: extension of transversalis
    • Tunica vaginalis: partietal and visceral
    • Tunica albuginea: fibrous connective tissue, thickens posteriorly to form mediastinum testis
    • Testicular lobules: divided by fibrous partition, contain seminiferous tubules
  3. Layers of seminiferous tubule
    • lamina propria - containing myoid cells that contract tubules
    • Leydig cells/interstitial cells: contain receptors for LH, produce testosterone
    • basement membrane
    • Germinal or seminiferous epithelium: Sertoli/Sustentacular cells and proliferative spermatogenic cells
  4. Sertoli cells
    • Columnar cells that rest on basement membrane
    • Elongated nucleus
    • Support, protect, and nourish proliferative cells
    • Secrete substances that regulate sperm production
    • Phagocytic
    • Protection of prolif cells from autoimmune attack
  5. basal and adluminal compartments
    • basal compartment of Sertoli cells develop tight junctions during puberty, prevent transduate from reaching adluminal compartment
    • blood-testis barrier: tightest blood-tissue barrier in mammals
  6. Spermatogenesis
    • Spermatogenic cell = spermatogonium
    • Division (MITOSIS) gives rise to one new germ cell (spermatogonium, resistant to radiation/chemo) and primary spermatocyte (committed cell)
    • Primary spermatocyte (2n) -> 2 secondary spermatocytes
    • Secondary spermatocyte (n) -> 2 spermatids
    • Spermatids undergo spermiogenesis until mature (non-motile - not mature-motile until past epididymis)
  7. Length of spermatogenesis and spermiogenesis
    What is spermiation?
    • spermatogenesis: 60d - spermatogenic cells stay connected to each other thru cytoplasmic bridges
    • spermiogenesis: 20d
    • spermiation: release of 128mil sperm into duct system/day
  8. Sperm
    • head - contains chromatin, acrosomal cap w/enzymes to digest ovum
    • tail - specialized cilium, referred to as flagellum - ATP and dynein activity
    • 35C optimal
  9. Maintaining temp for healthy sperm cells
    • 35C
    • pampiniform plexus of veins in scrotum dissipate heat
    • cremaster muscle & dartos muscle superficially contract to increase temp
  10. components of spermatic duct system
    • intratesticular ducts: straight tubules (Sertoli->simple cuboidal), rete testis (cimple cuboidal), efferent ducts (simple cuboidal ciliated/non-ciliated)
    • epididymis: pseudostratified columnar epithelium, stereocilia, sperm can be stored up to a month
    • vas (ductus) deferens: highly muscular (longitudinal and circular), pseudostratified, elastic fibers, adventitia
    • ejaculatory duct - like vas deferens w/o muscle
  11. accessory glands
    • 2 seminal vesicles - connects to vas deferens
    • prostate
    • two bulbourethral glands
    • produce secretions added - 90% of ejaculate
  12. seminal vesicles
    • lacy mucosa
    • pseudostratified columnar epithelium
    • secretion: PGs, fructose, fibrinogen, enzymes
    • coagulate semen after ejaculation
    • lamina propria rich in elastin
    • 2 layers of smooth muscle
  13. prostate gland
    • surrounds urethra @base of urinary bladder
    • milky fluid: citrate, Ca2+, enzymes
    • thru prostatic ducts
  14. Molecular mechanism of LH on Leydig cell
    • LH binds to G-coupled protein receptor
    • Adenylate cyclase-> increase cAMP, activation of PKA
    • Phosphorylation, synthesis of testosterone
    • cholesterol -> pregnenolone -> progesterone -> 17 alpha hydroxyprogesterone -> androstenedione -> testosterone
    • Aromatase converts to estradiol (not in Leydig)
    • 5 alpha reductase converts to dihydrotestosterone (not in Leydig)
  15. Testosterone distribution in plasma
    • 3% free
    • 30% bound to albumin
    • 67% bound to SHBG (sex hormone binding globulin/adrogen binding protein) - synthesized primarily in the liver
    • SHBG: prevent steroid diffusion into cells, increase half-life
  16. GnRH secretion
    • pulsatile; causes LH, FSH release to be pulsatile also
    • difficult to study because it's released in small amts in portal circulation, degraded quickly
    • Inhibin synth by Sertoli/granulosa cells inhibits FSH secretion
  17. Fetal male differentiation
    • Testes secrete testosterone when stim. by LH @16wks gestation
    • Wolffian ducts differentiate into seminal vesicles, epididymes, vas deferens
    • Sertoli cells secrete Mullerian Inhibiting Factor
    • External development of penis and prostate require 5 alpha reductase to convert testosterone to DHT
    • Lack of 5 alpha reductase = ambiguous external genitalia
    • Image Upload 1
  18. Hypothalamus-Pituitary-Testes pathway
    Image Upload 2
  19. Role of SRY
    • required for testicular development
    • testes make testosterone to stimulate Wolffian ducts, DHT stimulates development of male external genitalia, MIF would normally inhibit development of female internal genitalia
    • XY individual w/ SRY KO = phenotypic female
  20. Path of ureter in male
    • Under-over-under
    • Under testicular vessels
    • Over common iliac vessels
    • Under vas deferens
  21. What glands are located at the deep perineal space/pouch?
    Bulbourethral glands
  22. What is testicular feminization syndrome?
    • Lack of androgen receptors
    • Gonads still develop into testes (undescended), but labia majora will form
  23. What is required for spermatogenesis?
    • LH needed for testosterone secretion
    • FSH needed for normal Sertoli cell fx
    • Not required: DHT
  24. Inguinal triangle boundaries
    • Inferior epigastric vessels
    • Rectus abdominis
    • Inguinal ligament
  25. Andropause
    Decreases in muscle mass, libido, appetite, bone formation
  26. Indirect inguinal hernia
    Failure of processus vaginalis to close
  27. Direct inguinal hernia
  28. Finasteride and dutasteride
    • 5-alpha reductase inhibitor (type 2)
    • Prevent conversion of testosterone to DHT
    • Treatment of BPH, causes prostate to undergo atrophy/apoptosis
    • dutasteride inhibits type 1 and 2
  29. sildenafil
    • 5-phosphodiesterase inhibitor (PDE-5 inhibitor)
    • causes cGMP to remain elevated for longer than usual
    • NO has half life of seconds
    • half-life of 4hr, 40% bioavailability
    • helicine artery dilation
    • SE: headache, flushing, nasal congestion, color vision disturbance
    • No erection without arousal; cGMP should only be produced during arousal
  30. Micturition events
    • Sensory afferent signaling of bladder fullness to CNS
    • CNS modulated external sphincter relaxation
    • internal urethra/bladder neck relaxation
    • CNS-mediated increase in detrusor contractility
    • Urination
  31. Side effect of anti-cholingerics
    • Overflow incontinence
    • (Inhibition of normal bladder emptying)
  32. Incomplete distal closure of urethral folds
  33. Urinary changes with aging
    • Decreased bladder capacity and force of contractions
    • decreased ability to postpone voiding
    • decreased urethral compliance
    • Weakening of pelvic support muscles
    • increased postvoid residual volume
    • involuntary bladder contractions
    • nocturia 1-2x/night
  34. Parasympathetic tone of bladder
    • muscarinic receptors control parasymp tone of detrusor muscle
    • M2 receptors inhibit cAMP-mediated smooth muscle relaxation
    • M3 receptors directly cause contraction
  35. Estrogen deficiency: effect on bladder
    • reduced effectiveness of internal and external sphincters that have estrogen receptors
    • predisposition to urethritis, trigonitis, cystitis
    • vaginal atrophy
  36. TCA antidepressants: examples, mechs, and SE
    • amitriptyline/imipramine
    • indirectly-acting sympathomimetic, incr. [NE, 5HT]
    • SE: anticholingeric, treats urinary incontinence - blocks actions of ACh @ muscarinic receptors
  37. desmopressin
    • treatment for nocturnal enuresis
    • DDAVP, reduces urine production
    • SE: hyponatremia
  38. types of incontinence
    • overflow: partial voiding when bladder is full
    • stress: common in women, caused by pressure when laughing, sneezing, etc
    • urge: detrusor hypersensitivity
  39. tamsusolin
    • alpha-1 adrenergic antagonist, blocks contractile actions of NE on smooth muscle of internal sphincter
    • SE: orthostatic hypotension, can cause retrograde ejaculation
  40. Male sexual response
    • alpha adrenergics on helicine artery maintain vascular tone (non-aroused)
    • sympathetics stimulate smooth muscle in vas deferens, capsule of seminal vesicle, capsule/fibromuscular stroma of prostate during ejaculation
    • Parasympathetic stimulation -> release ACh, NO -> erection
  41. Penis: somatic and autonomic
    • somatic: pudendal nerve, dorsal nerve of the penis
    • for bulbospongious and ischiocavernosus, the perineal branch of the pudendal nerve
    • autonomic: cavernous nerve (innervating corpus cavernosum) from the prostatic plexus
    • sympathetic stimulation of cavernous nerve closes internal urethral sphincter, prevent retrograde ejaculation
  42. oxybutnin
    • blocks ACh binding to muscarinic receptors
    • increases bladder capacity
  43. tolterodine
    • antagonist at M3 receptors
    • most effective for urge incontinence
    • SE: dry mouth, constipation
Card Set
Male reproductive organs
reproduction block 3