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Reproductive System (Male Reproductive Structures (Testes (Seminiferous…

- - - - produce androgens: testosterone
    - - form the bulk of each testis
        
        Sertoli Cells
        
        sustenocyte
        
        Secrete signaling molecules that promote sperm production
        
        Can control whether germ cells live or die
        
        tight junctions btw these cells form blood-testis barrier
        
        keeps bloodborne substances from reaching germ cells
        
        keeps antigens from getting into bloodstream
        
        Germ cells
        
        Spermatogonium
        
        line the basement membrane inside the tubule
        
        produce primary and secondary spermatocytes
        
        then spermatids, which produce formed sperm
      - Composed of: developing sperm cells surrounding a lumen
        
        sperm cells are released from from the lumen into straight tubules, then into a fine meshwork of tubules (rete testes)
        
        sperm leave rete testes, and testes, through 15 to 20 efferent ductules that cross the tunica albuginea
  - - - takes 12 days for sperm to move thru epididymis
  - - - aka ductus deferens
      - thick muscular tube, bundled together inside scrotum
        
        w connective tissue, blood vessels, and nerves into structure called spermatic cord
        
        extends through inguinal canal into the abdominal walls, continues to pelvic cavity, ends posterior to bladders, dilates into ampulla
      - sealing a portion of vas deferens is the male form of birth control
  - - - pair ejaculatory ducts move seminal fluid into the prostate gland
  - - - critical to coagulate/decoagulate the semen after ejaculation
  - - - helps clean urine residues
        
        sometimes called pre-ejaculation
        
        possibly picks up sperm already present in urethra, may cause pregnancy
  - - - erectile tissue, spans lengths of shafter
      - Corpus Cavernosum
        
        2 large lateral chambers, make up bulk of penis
      - Corpus Spongiosum
        
        smaller chamber, surrounds the spongy urethra
    - - End of penis
      - high concentration of nerve ending, very sensitive
    - - foreskin
      - contains dense concentration of nerve endings
      - skin of shaft that extends down of the glans
      - lubricates and protects glans penis
    - - where semen and urine exit the body
- - - - each oocyte surrounded by supporting cells in bundle called a folllicle
  - - - pad of fat located over pubic bone
    - - folds of hair-covered skin that begin posterior to mons pubis
    - - thinner, more pigmented. medial to labia majora.
      - serve to protect female urethra and vaginal entrance
    - - organ with abundant nerves, important for sexual sensation & orgasm
  - - - Lactobacillus secretes lactic acid, maintains vaginal pH
        
        Pathogens should not be able to survive the acidic vaginal environment
  - - - Primordial follicles have only granulosa cells, can stay in this resting state for years
      - At puberty, a few of these cells will join a pool of growing follicles called primary follicles each day
        
        primary follicles see division of granulosa cells and become secondary follicles
        
        now have increase in diameter, new outer layer of connective tissue, blood vessels, and theca cells
        
        theca cells work with granulosa cells to produce estrogen
        
        Secondary follicles secrete zona pellucida, plays critical role in fertilization
        
        thick follicular fluid forms btw granulosa cells, begins to collect into pool called antrum
        
        follicles with large, fully formed antrum are considered tertiary follicles
  - - - isthmus is narrrow medial end connected to uterus
      - infundiblum flares out with slender, finger-like projections called fimbriae
      - ampulla: middle region, where fertilization often occurs
  - - - Cervix secretes mucus that can facillitatte sperm mvmt thru tract
    - - myometrium is responsible for contractions
      - endometrial layersL stratum basalis and stratum functionalis
        
        functional layer provides proper site of implantation for fertilized egg. sheds during menstruation
  - - - lactation
      - produced by mammary glands
        
        exits nipple via lactiferous ducts
- - - - during journey to uterus, zygote undergoes five or six mitotic cell divisions
        
        each cleavage results in more cells, called blastomeres
        
        3 days after fertilization, a 16-cell conceptus reaches the uterus, called morula
        
        continues to divide for several days, growing larger while endometrial lining thickens
        
        starts to secrete fluid and set up around a blastocoel. now referred to as blastocyst.
        
        within this, a group of cells form into an inner cell mass, fated to become the embryo
        
        cells forming the outer shell are called trophoblasts
        
        develop into chorionic sac and fetal portion of placenta
  - - - Transparent membranous sac that encloses the developing fetus and fills with amniotic fluid
    - - associated with primitive circulation to developing embryo
      - source of 1st blood cells, germs cells
        
        contributes to the umbilical cord structure
    - - finger-like outpocketing of yolk sac from the primitive excertory duct of the embryo
        
        precursor to urinary bladder
    - - develops for syncytiotrophoblast, cytotrophoblast, and mesoderm
      - surrounds the embryo, forms fetal position of placenta thru chorionic villi
  - - - differntiate and separate into an embryonic disc
        
        establish three primary germ layers (endoderm, mesoderm, ectoderm) see lab manual.
        
        embryonic folding
        
        fetus begins to take shape
- - - - ductus venosus, foramen ovale, ductus arteriosus
        
        enable it to bypass the semifunctional liver and pulmonary circuit until after birth
  - - - infant can now survive in the outside world
- - - - sperm counts slowly decline after age 35
  - - - See: Sperm Meiosis
      - from primary spermatocyte to secondary spermatocyte to spermatid to spermiogenesis cycle to spermatozoa
        
        formed sperm is the end result
        
        occurs in portion of the tubule nearest the lumen
        
        sperm are then released into the lumen, moved towards the epididymis for next step of sperm maturation
  - - - head contains nucleus and is covered in lysosomal enzymes
      - mid-piece contains mitochondria used to power flagellum
      - tail allows for mvmt, using flagellum
- - - - Leydig cells (interstitial cells) are located btw semiiniferous tubules in the testes
      - secreted by male embryos by seventh week of dev
        
        early release results in anatomical differntiation of male sexual organs
    - - Promotes spermatogenesis
      - role in muscle dev, bone growth, dev of secondary male characteristics, and maintaining libido
      - Ovaries produce small amts of testosterone
        
        most is converted to estradiol
        
        also secreted in adrenal glands, both sexes
    - - Controlled by hypothalamus and pituitary gland
      - GnRH from hypothalamus stimulates endocrine release of hormones from pituitary gland
        
        stimulates release of lutenizing hormone and follicle-stimulating hormone
        
        FSH binds to sertoli cells to promote spermatatogenesis
        
        also stimulate the release of inhibins, reducing testosterone secretion
  - - - causes coordinated mvmt the sweeps surface of the ovary and pelvic cavity
- - - - Lining is shed, the days that the woman menstruates
        
        stratum functional layer of uterus is layer being shed
      - 2-7 days
      - occurs during early days of follicular phase of ovarian cycle
        
        progesterone, FSH, LH levels are low
    - - Menstrual flow has ceased, endometrium begins to proliferate
      - Occurs when granulosa and theca cells begin to produce increased amts of estrogen
        
        will eventually lead to decreased FSH and stimulated LH, triggering ovulation
        
        usually occurs on day 14
        
        ovulation marks end of proliferation phase and follicular phase
    - - LH and esttrogen levels are high
        
        causes increased uterine tube contractions
        
        decreases vaginal acidity, making it more hospitable to sperm
      - In the uterus, progesterone from the corpus luteum begins the secretory phase
        
        endometrial lining prepares for implantation
        
        10-12 days, endometrial glands secrete fluid rich in glycogen
        
        if implantation has occurred, this fluid will nourish the ball of cells now developing from the zygote
        
        If no pregnancy occurs, the corpus luteum will degrade into the corpus albicans
        
        levels of estrogen and progesterone will fall, endometrium will grow thinner
        
        prostaglandins will be secreted, causing endometrial tissue death, resulting in menses
- - - - Primary oocytes are formed in fetal ovary prior to birth
        
        will remain in primary oocyte phase until puberty, stopping after menopause
- - - - Meiosis 1: each of the 23 pairs of chromosomes separate, resulting in 2 cells (secondary spermatocytes), each with only half the # of chromosomes
        
        Meiosis 2: occurs in both secondary spermatocytes, each of the 23 replicated chromosomes divide, similar to mitosis
        
        meiosis results in separating the chromosome pairs
        
        results in total of four cells,with only 1/2 the # of chromosomes
        
        each new cell is called spermatid
    - - For oocytes
        
        oocytes remain as primary until puberty, when LH triggers resumption of meiosis
        
        Resumption of meiosis causes transition into secondary oocyte
        
        cell division results in two daughter cells, one much larger than the other
        
        the larger daughter cell is the seconary oocyte, will eventually leave the ovary during ovulation
        
        Meiosis of secondary oocyte is completed only after a sperm penetrates it's barriers, then Meiosis 2 will occurs
        
        1 more item...
        
        small daughter cell is called polar body, may/may not complete meiosis to produce second polar bodies, will disentigrate