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Reproduction. Chapter 27. Male Reproductive System. Reproductive organs Testis Scrotum Reproductive tract Epididymis Vas Deferens Spermatic cord Accessory glands & organs Seminal vesicles Prostate gland Bulbourethral gland Penis. Gamete Production. Testes Spermatozoa (sperm)

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reproduction

Reproduction

Chapter 27

male reproductive system
Male Reproductive System
  • Reproductive organs
    • Testis
    • Scrotum
  • Reproductive tract
    • Epididymis
    • Vas Deferens
    • Spermatic cord
  • Accessory glands & organs
    • Seminal vesicles
    • Prostate gland
    • Bulbourethral gland
    • Penis
gamete production
Gamete Production
  • Testes
    • Spermatozoa (sperm)
    • ~100-300 million/ day
    • Production begins at puberty
  • Spermatogenesis- VERY temperature sensitive
      • Optimal temperature ~3-4C below body temp
scrotum
Scrotum
  • Bi-chambered external pouch of skin
  • Function
    • Houses testes
    • Protects testes
    • Regulates testicular temperature
  • Scrotum modifications for temperature regulation & protection
    • Low insulation- sparse hair & thin skin
    • Sweat glands
    • Vascularization- countercurrent blood flow
    • Musculature
    • Ennervation
low insulation
Low Insulation
  • Little insulating fat
  • Sparce hair
  • Sweat glands
musculature
Musculature
  • Dartos muscle (tunic)
    • Muscle inserting into scrotal skin
    • Contraction tenses skin of scrotum & raises testis
      • wrinkling
  • Cremaster muscle
    • Surrounds testis
  • Contraction pulls testis closer to body
    • Cold- contraction
    • Warm- relaxation
vascularization

Testes

Vascularization
  • Pampiniform plexus
    • Countercurrent blood flow
  • Cool venous blood surrounds incoming arteries
  • Actively cools incoming blood & warms outgoing blood
    • Testes always surrounded by cool blood
scrotum nerves
Scrotum Nerves
  • Behavioral protection
testis
Testis
  • Paired gonads inside of scrotum
  • Surrounded by tunic
    • Tunica albuginea
  • Function
    • Spermatogenesis- sperm formation
    • Hormone production
      • Androgens- testosterone
tunica albuginea
Tunica albuginea

“White Coat”

testis structure
Testis Structure
  • Seminiferous tubules
    • Sertoli cells
  • Rete testis
  • Interstitial (Leydig) cells
seminiferous tubules
Seminiferous Tubules
  • Actual site of spermatogenesis
  • 800+ coiled tubes
    • Maximizes surface area
  • Bulk of testes tissue
interstitial leydig cells
Interstitial (Leydig) Cells
  • Located between seminiferous tubules
  • Site of androgen production
  • Surrounded by capillaries
  • Stimulated to produce by increased levels of testosterone by Leuteinizing Hormone
sertoli cells
Sertoli Cells
  • Lots tight junctions in cells near basement membrane
  • Form blood testes barrier
  • Protects from pathogens, mutagens, immune cells
sperm path
Sperm Path

Male reproductive tract continuous- Isolates sperm

rete testis
Rete Testis
  • Located within the testis
  • Site of merging seminiferous tubules exiting from testes
  • Common pathway for exiting sperm
epididymis
Epididymis
  • Testicular cap
  • Single coiled tubule
    • 6M long
  • Receives sperm from rete testis
  • Function
    • Secretes/absorbs nourishing fluid
    • Recycles damaged spermatozoa
    • Stores spermatozoa
      • Up to 2 weeks
      • Allows time for maturation
tunica vaginalis
Tunica Vaginalis

Surrounds testes & epididymis

Allows free movement of testes inside of scrotum

vas deferens
Vas Deferens
  • Aka Ductus Deferens
  • Single tubule carries sperm from epididymis into abdominal cavity
    • 45 cm long
  • Muscular tube
  • Passes thru inguinal canal
  • Connects to urethra at prostate
spermatic cord
Spermatic Cord
  • Tissue located within the inguinal canal
  • Combination of tissues
    • Vas deferens
    • Pampiniform plexus
    • Testicular tissue
    • Arteries & nerves
    • Muscle
accessory glands
Accessory Glands
  • Seminal vesicle
  • Prostate
  • Bulbourethral gland
accessory glands44
Accessory Glands
  • Secrete seminal fluid
  • Nourish, activate & protect sperm
  • Semen (seed)
    • Glandular secretions (99%) & sperm (1%)
    • ~2-5 mls per ejaculation
    • ~50-200 million sperm per ml of ejaculate
      • 100-700 million per ejaculation
      • 50 reach oocyte
seminal vesicle
Seminal Vesicle
  • Paired elongate glands
  • Located posterior & inferior to bladder
  • Secretes (60% semen)
    • Fructose
      • “sugar”
      • Energy source
    • Prostaglandins
      • Activate sperm motility
      • Stimulate contractions of female reproductive tract
    • Fibrinogen
      • Clotting factors
      • Slows sperm
prostate
Prostate
  • Large solid single gland
  • Located at base of bladder
  • Houses prostatic urethra
  • Secretes (20-30%)
    • Enzymes
      • Aid in activating sperm motility
      • Antibiotic
      • Mucus degradation
    • Alkaline fluid
      • Neutralize female reproductive tract
    • Citric acid, proteolytic enzymes
    • Antioxidants
    • ???secretions of unknown function
prostate cancer
Prostate Cancer
  • Most common cancer in men
    • 3rd most common cause of death in men
  • Disease of well developed nations
  • Diet & lifestyle
    • High fat diet
    • High testosterone levels
    • Cadmium exposure
    • Low rates in Japanese & vegetarians
  • By age 80 70% men will have it
bulbourethral gland
Bulbourethral Gland
  • Small paired gland
  • Located at the base of the penis
  • Secretes alkaline mucus
    • Neutralize urinary acids
    • Lubrication
penis
Penis
  • Copulatory & excretory organ
  • Excretory
    • Penile urethra
    • Carries urine & sperm
  • Copulatory
    • 3 cylindrical masses or erectile tissue
    • 2 corpora cavernosa (rt & lt)
    • Corpus spongiosum
corpora cavernosa
Corpora Cavernosa
  • Right & left
  • Primary erectile tissue
  • Paired superior masses
  • Provides the majority of rigidity & length
    • Pulls urethra taught by pushing glans
  • Crus
    • posterior expansions
    • “anchor” tissue against pelvic bone
sinusoids trabeculae
Sinusoids & Trabeculae

Smooth muscle holds closed

Vasoconstriction

erectile tissue
Erectile Tissue

Sinusoids & Trabeculae

  • Muscle holds chambers closed
  • Relaxation of muscles opens chambers
  • Blood vessels open
  • Chambers become blood filled to result in erection
viagra
Viagra
  • Dilates blood vessels
viagra health risks
Viagra Health Risks
  • Effects blood flow
    • Lowers blood pressure
    • Heart attack
  • Effects color vision
  • Opens arteries in brain
  • Addiction
corpora spongiosum
Corpora Spongiosum
  • Inferior mass
    • Secondary erectile tissue
  • Contains Penile urethra
  • Glans
    • Anterior expansion
  • Bulb of penis
    • Posterior expansion
  • Prepuce
    • Folds of skin covering glans
prepuce
Prepuce
  • Protects
  • Produces smegma
    • Waxy substance
male female comparison
Penis

Corpora cavernosa

Corpora spongiosum

Prox shaft of penis

Prostate

Bulbourethral glands

Scrotum

Clitoris

Corpora cavernosa

Corpora spongiosum

Labia minora

Paraurethral glands

Grtr vestibular gland

Labia Majora

Male-female Comparison
testicular cancer
Testicular Cancer
  • Most common form of cancer in men ages 15-35
  • Very treatable with early detection
  • 8250 cases diagnosed in 2006
  • Less 400 expected to die
  • Caucasians most suseptable
  • Rates doubled in last 30-40 yrs