Reproduction

  1. Functions:

    1. ensure continuity of the species
    2. production of gametes (germ cells)
    3. production of sex hormones
      1. growth of various organs
      2. influence drives & behavior
    4. transport, protect, nourish gametes after leave the gonads

  2. Male Anatomy

    1. Embryonic development
      1. similar until the presence of male sex hormone (testosterone) produced to cause differentiation ~ 7th week
        1. injection of Testosterone into XX--> develop male pattern
      2. sex of embryo is determined at fertilization.
    2. Primary sex organ - testes
      1. produce sperm and androgens
      2. develop retroperitoneal, just below kidneys
      3. descend into scrotum along with blood supply
        1. ~2 months before birth (cryptorchidism)
        2. Scrotum is the pouch holding testes
        3. suspended from body (3degrees C cooler for sperm)
        4. Inguinal canal remains weakened and is a potential site for hernia (intestine protrudes out of abdominopelvic cavity)
      4. Dartos muscle (below skin)--> wrinkling
      5. Cremaster muscle
        1. elevates testes is continuation of abdom. oblique muscle
      6. Seminiferous Tubules
        1. produce sperm 'spermatogenesis'
      7. Intersitial cells (Leydig)
        1. secrete testosterone (important androgen)
      8. Sustentacular (Sertoli cells)
        1. support immature sperm cells,
        2. secrete hormones: Inhibin, androgen binding protein (ABP)
      9. Testis surrounded by tunica albuginea (white)
        1. divide testis into lobular compartments with seminifierous tubules.
          1. lead into tubulus rectus -->into network of tubes (rete testis)
          2. these empty into efferent ductules which connect to epididymus
    3. Accessory organs: scrotum, ducts, penis
      1. Duct System:
        1. Epididymus - first part of duct system coiled tube in scrotum posterior to testes
          1. temporary sperm storage (non-motile)
          2. usually ~ 12-20 day journey required for maturation
          3. propelled into urethra or reabsorbed
          4. smooth muscle contracts with ejaculation
        2. Ductus deferens (vas)
          1. continuation of epididymus (cilia, peristalic)
          2. pass along posterior of testes ascending through scrotum (inguinal canal)
          3. enclosed in fascia (spermatic cord) w/ nerves, blood vessels
          4. runs superior into pelvic cavity behind urinary bladder
          5. ampulla joins w/ seminal vesicle duct to form ejaculatory duct urethra)
          6. joins prostatic urethra
          7. vasectomy - sterilization ducts are tied off, excised
            • no effect on sexuality
      2. Urethra
        1. Dual function - same 3 parts: prostatic, membranous, spongy
        2. Spongy passes thru corpus spongiosum (penile urethra)
          1. delivers sperm to female
      3. Penis
        1. copulatory organ to place spermatozoa in female tract.
        2. part of external genitalia (+ scrotum)
        3. prepuce (foreskin) can be circumcised
        4. ends in enlarged tip (glans)
        5. 3 columns of erectile tissue (vascular)
          1. corpora cavernosa (2 dorsal)
          2. corpora spongiosum (1 ventral)
        6. Semen
          1. alkaline to enhance sperm motility (slow in acid)
          2. 50-100 million sperm / ml
          3. Infertility: less than 20 million/ml
            • marijuana, alcohol, drugs (antibiotics) may affect sperm count, motility morphology (2 heads)
    4. Accessory glands:
      1. Seminal Vesicles:
        1. found at base of posterior bladder
        2. provides 60% semen volume
        3. alkaline fluid pH ~7.5 to neutralize acidic female tract
        4. contains fructose (nourish,energy), prostaglandins (motility in female)
        5. mix w/ sperm in ejaculatory duct precursor for clotting of semen
      2. Prostate gland
        1. secrete milky, acidic (citrate, proteolytic enzymes -PSA)
        2. 25% of semen volume
        3. motility & viability of sperm
        4. liquefy coagulated semen
        5. hypertrophy occludes urethra
      3. Bulbourethral glands (Cowper's)
        1. pair of small glands below prostate at membranous urethra
        2. secrete thick alkaline mucus (early in sexual stimulation) to neutralize acidic urine
        3. analogus to Bartholin's glands in female

  3. Female Reproductive Anatomy

    1. Gonads = ovaries (male- testes)
      1. produce ova (gametes)
      2. produce sex hormones, estrogens and progesterone
      3. held in pelvis via broad ( holds tubes, uterus), ovarian ligament
      4. internal follicles embedded in stroma (vascular)
      5. contain ~700,000 primoridal follicles
        1. (undeveloped ovum or oocyte) only 400 mature
        2. mature follicle = Graafian follicle
        3. follicles are at different stages of maturation
        4. Rupture of follicle (thru granulosa layer) = ovulation
        5. follicle then becomes the Corpus Luteum (eventually degenerates)
        6. CL or (yellow body) is producer of sex hormones, if no fertilization--> degenerates
    2. Uterine Tubes (Fallopian)
      1. ciliated, fingerlike projections (Fimbriae)
        1. not continuous w/ ovary
        2. expanded curved region near ovary (ampulla) - site of fertilization
      2. Isthmus connects to uterus
      3. salpingitis- inflammation of tubes
      4. tube closure is a cause of infertility
    3. Uterus (womb)
      1. hollow, pear-shaped organ
      2. fundus- body-- isthmus- cervix
      3. normally anteverted (forward slant)
      4. bladder anterior, rectum posterior
      5. Walls:
        1. perimetrium (serosa)
        2. myometrium (smooth muscle-contraction)
          1. myometrium is thickest layer, contractile in labor
        3. endometrium (secretory epithelium)
          1. functional layer of endometrium thickens, vascular in preparation for ovum
          2. endometriosis - growth of tissue outside of uterus (Tubes, colon, bladder)
          3. endometrium has 2 layers with different sets of arteries
            • spiral arteries outside layer undergo repeated degeneration & spasm (menses)
    4. Vagina -' birth canal'
      1. passage of infant & menses
      2. acidic (pH 3.5-4.0 due to anaerobic bacteria use of glycogen)
      3. extends from cervix of uterus
      4. mucosa contains rugae
      5. distal end has fold (hymen) -not reliable to determine virginity
    5. External Genitalia
      1. Vulva:
        1. Labia Majora (homologue to scrotum)
        2. Labia Minora (delicate enclosure of vestibule- homologue (spongy urethra)
      2. Vestibule:
        1. Clitoris (homologue to glans penis)
          1. has corpora cavernosa
        2. urethral opening
        3. Vagina - flanked by Bartholins (vestibular glands)
      3. Female: reproductive & urinary separate
        1. neither are associated with Clitoris

  4. Male reproductive physiology

    1. Spermatogenesis: birth of sperm in seminiferous tubules (~ 70 days)
      1. involves meiosis (nuclear division occuring in gonads)
        1. daughter cells 1/2 # of chromosomes (23) = haploid
      2. Mitosis (cell division of othe body cells) - replication of same # chromosomes (46)
        1. Gametes - haploid (23)
        2. Allow to fuse w/ other gamete (zygote) = 23 pairs 1 paternal, 1 maternal
      3. Meiosis:
        1. reduces chromosome # in half
        2. allows genetic variability 46 chromosomes = diploid
        3. In seminiferous tubules:
          1. stem cells--> spermatogonia which divide mitotically until puberty
          2. spermatogenesis starts at puberty when mitosis results in 2 daughter cells
      4. mitosis results in 2 daughter cells:
        1. stays in basement membrane
        2. goes to lumen where primary spermatocyte becomes 4 spermatids
          (2 meiotic divisions)
          1. has 23 chromosomes but nonmotile
          2. spermatids become spermatozoa
            • contain head, midpiece, tail (motile)
            • acrosome- hydrolytic fluid
            • mid-piece - provides contractile energy
      5. Sertoli cells = 'blood testis barrier'
        1. prevent auto immune response to haploid cells
        2. 1 primary spermatocyte become 4 spermatozoa (via 2 meiotic divisions)
    2. Male sexual response
      1. Erection - parasympathetic (sacral reflex)
        1. corpora cavernosa (blood engorged)
        2. CNS input
      2. Ejaculation - sympathetic (L1-L2)
        1. peristaltic -ducts & accessory glands
        2. bladder constricts
        3. penile arterioles dilate w/ parasym (compress veins), then sympathetic constricts arterioles

  5. Female Reproductive Physiology

    1. Oogenesis
      1. analogus to spermatogenesis (in ovary)
      2. oogonia mitotic (46 chromosomes) until birth
        1. become primary oocyte found in follicle
        2. no development until puberty
      3. 1st meiotic division of primary oocyte:
        1. 1st polar body ( little cytoplasm-degenerates
        2. Secondary oocyte (23) (Ovulated)
      4. secondary oocyte
        1. Only completes meiosis if sperm enters
        2. results in 1 Mature ovum + 2nd polar body
        3. 1st polar body --> 2 polar bodies
      5. Ovum (23) + Sperm (23)
        1. results in 1 ovum + 3 polar bodies
      6. oogenesis until menopause
    2. Ovarian cycle: 3 phases ~ 28 days
      1. follicular Day 1- 10 Follicle growth
      2. ovulatory Day 11-14 oocyte release
      3. Luteal Day 14-28 'corpus luteum'
        1. following ovulation (cause by LH surge)
        2. if fertilization CL maintained, if not albicans
      4. Ovulation ' mittelschmerz'
        1. basal body temperature increases .5degrees F, mucus clear (progesterone thermogenic)
      5. Hormonal control is cyclic more complex
        1. GnRH (hypothal)--> +LH
        2. FSH (pituitary) FSH--> follicle
        3. LH--> theca cells (androgens convert to E)
        4. lo level Estrogen--> Neg. Feedback on FSH, (Inhibin), LH, GnRH so that only 1 follicle matures:
        5. Increases in estrogen --> LH surge (final maturation of follicle, ovulation)
      6. Key points:
        1. FSH--> follicle growth
        2. LH --> estrogen production by theca cells of follicle
        3. Very Hi estrogen --> + feedback LH surge (ovulation)
        4. Corpus Luteum --> Progesterone (responsible for secretory phase of uterine cycle)
        5. if Estrogen Progesterone decreases --> Menstrual Phase
    3. Uterine (menstrual) cycle - changes of endometrium to ovarian hormones
      1. Phases:
        1. Menstrual: Day 0-5
          1. shed, spiral arteries spasm
        2. Proliferative: Day 6-14
          1. increases in Estrogen --> increases thickening lining
        3. Secretory phase: Day 15 -28
          1. Corpus Luteum --> increases progesterone
          2. develops secretory mucosa
          3. CL dies if no fertilization, drop in progesterone
          4. no nutrition: cells die, arteries spasm
        4. Amenorrhea - absence of menses
        5. Oligomenorrhea - irregular menses
        6. Dysmenorrhea - painful menses
        7. Progesterone
          1. inhibits uterus motility during pregnancy (gestation)
          2. lactation
        8. Estrogen
          1. follicle growth
          2. oogenesis
          3. maturation of reproductive tract
          4. secondary sex characteristics
    4. Female sexual response
      1. Masters & Johnsons (1966)
        1. 'tenting' of uterus, inner vagina
      2. Similar to Males:
        1. same neural pathway
        2. corpus cavernosa (blood engorged)
      3. Differences:
        1. No ejaculation
        2. Not required for fertilization
        3. No refractory period