The Reproductive System

Primary sex organs (gonads): testes and ovaries

Accessory reproductive organs: ducts, glands and external genitalia

Male Reproductive System: Testes produce sperm released through ducts

  • Testes: within the scortum

  • Ducts: epididymis, ductus deferens, ejaculatory duct, and urethra

  • Accessory sex glands: seminal glands, prostate, and bulbourethral glands

The Scrotum: sac of skin and superficial fascia

  • outside abdominopelvic cavity

  • paired testes

  • below body temp.

  • septum divides into two

  • 3C lower than core body temperature

  • Lower temperature is necessary for sperm production

Midline septum divides scrotum into two compartments, one for each testis

  • Dartos muscle: smooth muscle, pulls Scrotum close to body

  • Cremaster muscles:skeletal muscle - elevate

The Testes:

Membranes:

  • Tunica vaginalis: outer, derived from peritoneum

  • Tunica albuginea: inner layer forms fibrous capsule

Septa: divides testes into lobules

  • 1250 lobules each

  • 1-4 seminiferous tubules

    • site of sperm production

Seminiferous Tubules:

  • Myoid cells surround each tubules - smooth muscle - like cells squeeze sperm and testicular fluids out of testes

Epididymis: 3 sections: head, body, tail


Blood supply:

  • arteries from abdominal aorta

  • veins form pampiniform venous plexus surrounding arteries - absorb heat from testicular arteries; keeps testes cool

Spermatic cord encloses nerve fibers, blood vessels, and lymphatics that supply testes

Homeostatic Imbalance:

  • Testicular cancer

    • rare, but most common cancer in men age 15-35

      • having mumps that lead to orchitis (inflammation of testis) could be a risk factor

      • cryptorchidism is most common risk factor

        • non descent of testes

    • sign: painless, solid mass in testis

    • 90% cured by surgical removal of testis and often radiation or chemotherapy

Penis:

  • corpus spongiosum: surrounds urethra and expands to form glands and bulb

  • corpora cavernosa: paired dorsal erectile bodies

Male Duct System: ducts carry sperm from testes to body exterior

  • Epididymis: 6m long

    • microvilli(stereocilia) absorb testicular fluid and pass nutrients to stored sperm

    • sperm: 20 days to become motile

    • contracts, expel sperm into ductus deferens

  • Ductus Deferens(vas deferens): 45 cm long

    • joints duct of seminal vesicle to form ejaculatory duct

    • smooth muscle in walls: propels sperm from epididymis to urethra

    • vasectomy: cutting and ligating ductus deferens (100% birth control)

  • Ejaculatory duct

  • Urethra: transports urine and semen

    3 regions:

    • prostatic urethra

    • intermediate (membranous urethra): in urogenital diaphragm

    • spongy urethra: runs through penis; opens at external urethral orifice

Male Accessory Glands:

  • Seminal glands:

    • smooth muscle contracts during ejeculation

    • viscous alkaline seminal fluid

    • duct joints ductus deferens to form ejaculatory duct

  • Prostate:

    • encircles urethra inferior to bladder

    • smooth muscle that contracts during ejaculation

    • secretes milky, slightly acid fluid

    • plays a role in sperm activation

    • Prostate Cancer:

      • second most common cause of cancer death in males

      • digital exam screening, PSA levels

        • biopsy if abnormal

      • treated with surgery and sometimes radiation, castration , drugs

      • in clinical trials: cryosurgery, chemotherapy, ultrasound, proton beam therapy

  • Bulbourethral glands:

    • pea sized glands inferior to prostate

    • thick, clear mucus during sexual arousal

    • neutralize traces of acidic urine in urethra

    • lubricate glands penis

Semen: sperm and accessory gland secretions

  • contains fructose of ATP production, protects and activates sperm, and facilitates sperm movement

  • alkaline fluid

Female Reproductive Anatomy: reproductive role of female more complex because of pregnancy

Ovaries: female gonads

  • Ligaments: suspensory ligament and mesovarium are part of broad ligament that supports uterine tubes, uterus, and vagina

  • Tunica albuginea:

    • fibrous, covers ovaries

    • covered by germinal cuboidal epithelium outer layer (continuation of peritoneum

  • Two poorly defined regions:

    • outer cortex: houses forming gametes

    • inner medulla: contains large blood vessels and nerves

  • Ovarian follicles: tiny saclike, embedded in cortex

    • contain immature eeg (oocyte)

    • go through several stages of development

  • Ovulation:

    • ejection of oocyte from ripening follicle

Female Duct System: tube system includes:

  • Uterine tubes: regions of uterine tube

    • isthmus: constricted area, joins uterus

    • ampulla: distal ends, curves around ovary

    • infundibulum: distal extension near ovary, ciliated fimbriae

  • Homeostatic Imbalance: Uterine Tubes

    • Ectopic pregnancy:

      • oocyte is fertilized in peritoneal cavity or distal uterine tube and begins developing there

        • normally abort naturally with substantial bleeding

    • Pelvic inflammatory disease (PID)

      • spread of infection from reproductive tract to peritoneal cavity

        • may cause scar tissue and lead to infertility

  • Uterus:

    • hollow, thick walled, muscular organ

    • receive, retain, and nourish fertilized ovum

    • position of uterus

      • Anteverted: inclined forward (normal position)

      • retroverted: inclined backward

  • Homeostatic Imbalance: Uterus

    • Cervical cancer

      • risk: frequent cervical inflammation; STIs, including HPV; or multiple pregnancies

      • Papanicolau (Pap) smear for detection

    • Prolapse of the uterus: unsupported uterus may sink inferiorly, until tip of cervix protrudes through the external vaginal opening

      • causes: overstretching & tearing muscles during childbirth

  • Uterine Wall: three layers of wall

    • perimetrium: outermost (visceral peritoneum)

    • myometrium: middle, layers of smooth muscle

      • contracts rhythmically during childbirth

    • endometrium: mucosal lining

      • simple columnar epithelium

      • fertilized egg burrows into endometrium

      • stratum functionalis - shed

      • stratum basalis - base layer

  • Vagina:

    • thin-walled tube 8-10 cm (3-4 inches) in length

    • birth canal, passageway for menstrual flow, copulation

    • vaginal secretions acidic in adult females, alkaline in adolescents

Sperm Production:

  1. the golgi apparatus packages the acrosomal enzymes

  2. the acrosome forms at the anterior end of the nucleus and the centrioles gather at the opposite end

  3. microtubules form the flagellum

  4. mitochondria multiply and cluster around the proximal portion of the flagellum

  5. excess cytoplasm sloughs off

  6. an immature sperm that has just been released from a sustentocyte

  7. structure for a fully mature sperm

Egg Production:

  1. Primordial follicle with a primary oocyte

  2. Primary follicle

  3. Secondary follicle

  4. Graffian follicle

  5. Corpus Luteum

Fetal Development: major understandings:

  • Fertilization:

    • sperm travels from vagina → cervix → uterus → fallopian tubes

    • when encounter egg, sperm uses enzymes form acrosome to disintegrate zona pellucida surrounding egg

    • only one can penetrate to fuse nucleus with nucleus of egg

    • fertilized egg = zygote

    • divided into 2 cells = embryo

    • keeps dividing & traveling down fallopian tubes until reaches uterus

  • Development:

    • day 4: solid ball of ~50 cells

    • day 5/6: blastocyst (hollow ball w/ fluid in center)

    • day 6/7: attaches to uterus after fertilization

    • ~3 weeks: nervous & digestive system develop

    • placenta: connection between mother & embryo, function: nourishment, respiration & excretion, barrier to disease, materials diffuse across capillaries

    • 8 weeks = fetus

    • 12 weeks = umbilical cord

      • 8 cm long, 28g

      • reflexes and movement

    • 4-6 months = specialization

    • 6+ months: can survive

      • mass doubles, lungs finish

  • Fetal testing:

    • ultrasound

    • genetic tests:

      • alpha fetoprotein: check for down’s syndrome and spinal bifida

      • amniocentesis: 16 weeks +

      • Chorionic Villus sampling: 10 weeks