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Reproductive system, The granulosa cells are what SURROUNDS the primary…

- - - - penis
        
        made up of
        
        erectile tissue corpus spongiosum
        
        corpus cavernosum
      - scrotum
        
        made up of
        
        testes
        
        testosterone and sperm are made here
        
        sperm pathway
        
        sperm is stored in the epididymis after production
        
        in ejaculation it travels through the ductus deferens(vas deferens)
        
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        epididymis is around 6 m long
        
        is made up of over 1000 coiled seminiferous tubules (around 150 cm long)
        
        the seminiferous tubules contains Sertoli cells and developing sperm
        
        outside the seminiferous tubule are the Leydig cells (interstitial cells)
  - - - site of spermatogenesis
    - - regulate spermatogenesis and maintain developing sperm cells through spermatogonia
      - also produces inhibin
      - also secretes fluid that pushes immature sperm to the epididymis and form the blood-testis barrier (BTB)
        
        The BTB isolates developing sperm cells from blood so immune cells do not attack them
        
        If the BTB did not develop properly, immune cells would attack the developing sperm cells because they are genetically different
        
        causes sterility
    - - found in the interstitial space between seminiferous tubules and produce testosterone
    - - final maturation area and storage site for sperm
    - - carries sperm from epididymis to the ejaculatory duct
        
        the ejaculatory duct drains into the urethra
    - - contributes a large portion of fluid to the semen in ejaculation that is rich fructose and enzymes to maintain and nourish the sperm
    - - secretes fluid that helps neutralize pH and lubricate urethra and vagina (creates optimal environment for sperm)
    - - transports sperm during ejaculation and drain the bladder during urination
  - - - these cells contain 46 chromosomes and will divide by mitosis where 1 cell remains spermatogonia nd other develops into a primary spermatocyte
        
        both of the new cells still have 46 chromosomes
        
        the primary spermatocyte divides by meiosis into 2 secondary spermatocyte in the first meiotic division
        
        secondary spermatocytes divide into four spermatid in the 2nd meiotic division
        
        spermatids have only 23 chromsomes
        
        spermatid develop into sperm cells
        
        sperm cells are released by Sertoli cells into the lumen of seminiferous tubules
        
        sperm cells take 12 days to mature in the epididymis
        
        sperm cell conponents
        
        head with acrosome and nucleus
        
        midpiece with mitochondria
        
        long flagellum propelling the sperm when it fully matures
        
        during this time, the dividing cells are surrounded and nourished by Sertoli cells, moving to the center of the tubule
        
        meiosis 1 is when the chromosomes go from 2n to n
  - - - follicle stimulating hormone (FSH) and luteinizing hormone (LH) aka interstitial cell stimulating hormone (ICSH)
        
        these hormones are released in response to gonadotropin releasing hormone (GnRH) from the hypothalamus
        
        FSH acts on Sertoli cells
        
        promotes spermatogenesis
        
        this also causes production of inhibin
        
        inhibin feeds back to the anterior pituitary and decreases LH and FSH hormone release
        
        LH stimulates Leydig cells to produce testosterone
        
        testosterone is important for spermatogenesis and will feedback, inhibiting LH and FSH production
  - - - one intermediate is progesterone, one of the female hormones
    - - the first peak of testosterone is during fetal development for make the male reproductive tract and external genitalia
        
        testosterone spikes again about birth for unknown reasons
        
        testosterone then remains low until puberty
        
        puberty is the transition from a non-reproductive to a reproductive state (period between 9-14)
        
        GnRH increases during this time (unknown reason) leading to increase LH and FSH levels, causing testosterone levels to increase
        
        the testosterone levels peak at 16-18 and this is the final sexual maturity stage of males
        
        at 40 years, there is a slow testosterone decrease and at 50 sperm production decreases
        
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    - - the male reproductive tract and external genitalia develops in the embryo
      - male reproductive organs grow and develop at puberty
      - development of male secondary sex characteristics
        at puberty (i.e. pubic hair)
      - sex drive at puberty
      - spermatogenesis
      - bone and skeletal muscle growth
      - increased aggressiveness
- - - - clitoris
        
        mound of erectile tissue that comes from same embryonic tissue as the penis
      - labium majus (aka labia majora)
        
        derived from the same embryonic tissue as the scrotum
      - labia minus (aka labia minora)
        
        surrounded by the labium majus
        
        derived from same embryonic tissue as the shaft of the penis
      - vaginal orifice
        
        enclosed by the labium minora
        
        opening to the vagina
    - - vagina
        
        where the penis goes during sex and where the sperm is deposited
      - when the sperm is deposited it travels through the cervix
        
        it then goes to the uterus
        
        aka the womb and is a muscular and hollow organ
        
        sperm then goes to the fallopian tubes (aka uterine tubes)
        
        around 20 cm long
        
        sperm's final destination is the fimbria (portion connected to fallopian tubes)
        
        when eggs made in the ovaries are released, it travels through the fimbria to the fallopian tube where it meets the sperm
  - - - receive the penis
      - allow for discharge of fluid during mensturation and birth of the baby
    - - secretes different types of muscus during the menstrual cycle
        
        thin mucous is to allow sperm entry
        
        thick mucus is to prevent sperm entry
    - - site where fertilized egg is implanted and where the developing embryo is nourished and maintained
      - the uterus lining goes through many phases during the menstrual cycle with hormone control
    - - where fertilization happens
      - they have cilia that pass the egg from the fimbria to the uterus
    - - captures the egg after being expelled from the ovaries, funneling it to the infundibulum
    - - produce eggs through oogenesis as well as estrogen and progesterone
      - oogenesis
        
        the time where the egg develops
        
        in egg development, it starts in a follicle
        
        starts with the production of million of oogonia in the developing female embryo
        
        this develops into the a primary follicle which is a granulosa cell single outer layer containing the primary oocyte
        
        granulosa cells then secrete a fluid into the interior of the follicle, forming the antrum
        
        this form is preserved until puberty
        
        puberty
        
        ovaries are activated by gonadotropic hormones, LH and FSH
        
        the female begins her menstrual cycle where few primary follicles start growing
        
        after puberty primary follicle develops into the theca cells found outside the granulosa cells
        
        the primary follicle slowly enlarges into a mature follicle
        
        here the oocyte separates from the granulosa cells, floating freely into the antrum before ovulation
        
        oogenesis only creates only viable oocyte where as spermatogenesis creates millions of sperm
      - Ovulation
        
        when the follicle grows, estrogen release increases
        
        estrogen causes granulosa cells of the follicle to grow and produce more estrogen
        
        the estrogen causes a positive feedback such that it increases FSH and LH
        
        A surge of LH causes the granulosa cells to secretes large amounts of fluid into the antrum, causing swelling, rupture and expelling the egg
        
        the egg is gathered by the fimbriae into the fallopian tube
        
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      - hormones in the ovaries
        
        estrogen
        
        estrogen is a group of hormones that includes
        
        17B estradiol (aka estradiol)
        
        this is the main estrogen secreted by the ovaries
        
        more powerful than estrone or estriol
        
        estrone
        
        estriol
        
        formation of estrogen
        
        follows the same pathway as testosterone using cholesterol
        
        difference is the estrogen reaction extends from androstenedione instead of turning to testosterone
        
        theca cells take up cholesterol
        
        LH stimulates theca cells to convert cholesterol into androstenedione
        
        very little androstenedione is converted to estriol by theca cells
        
        most androstenedione is secreted and taken up by adjacent granulosa cells
        
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        varying levels of estrogen
        
        estrogen is low until puberty
        
        increased estrogen causes increased secretion of gonadotropin releasing hormone (GnRH) from the hypothalamus
        
        Increase of GnRH increases LH and FSH release in the anterior pituitary
        
        estrogen levels decline in adulthood
        
        at age 40-50, menstrual cycles become irregular and ovulation sometimes does not occur
        
        the cycles stop at around age 50
        
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        this period is called menopause
        
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        progesterone
        
        a steroid hormone that is produced early in the testosterone/estrogen reaction
        
        normally produced in small amounts by granulosa cells and theca cells before ovulation
        
        these cells can be stimulated by LH to increase progesterone production
        
        (after ovulation) when the follicle degenerates into the corpus luteum, it will secrete estrogen and progesterone
        
        this estrogen and progesterone secretion is to prepare the lining of the uterus for the implantation of the fertilized egg
        
        if fertilization fails, the corpus luteum develops into scar tissue called corpus albicans
  - - - menses (day 0-7)
        
        low levels of LH, FSH, estrogen and progesterone
        
        the uterine lining is lost
      - proliferative phase (day 7-14)
        
        the follicle increases estrogen production
        
        this increases LH surges
        
        the follicle then ruptures, releasing the egg where the growth of the uterine lining is stimulated by estrogen and progesterone
      - secretory/luteal phase (day 14-28)
        
        the follicle develops into the corpus luteum and produces more progesterone to prepare the uterus for implantation
        
        if fertilization does not occur, the corpus luteum degenerates into the corpus albicans (scar tissue) and progesterone levels drop
    - - has synthetic hormones
        
        synthetic estrogen
        
        synthetic progesterone
        
        produces a thick cervical mucous inhibiting sperm entry to the uterus
        
        progesterone decreases uterus and fallopian tube mobility
        
        these structures normally help transport egg and sperm to the site of fertilization
      - if both hormones are included
        
        feedback to hypothalamus, decreasing GnRH
        
        feedback to anterior pituitary to decrease LH and FSH
        
        low FSH supress follicle development whereas low LH prevents LH surges which in turn prevents ovulation
- - - - The egg always contains an X chromosome
      - The sperm can contain an X or a Y chromosome
        
        If sperm has X chrom, combining with egg, it makes a girl
        
        If sperm has Y chrom, combining with egg, it makes a boy
  - - - forms the testes in the male/ovaries in the female
        
        Y chromosomes cause testes development at 6-7 weeks in the indifferent gonads (male embryos)
        
        the external genitalia and reproductive tracts are made next
        
        XX chromosomes cause ovary development at 9 weeks (female embryos)
    - - Wolffian duct
      - Mullerian duct
      - development of male fetus
        
        at 7 weeks, Mullerian inhibiting hormone (MIH) is secreted
        
        MIH regresses (turns back to less developed state) the Mullerian duct
        
        at 9 weeks, testicular cells starts producing testosterone
        
        the testosterone surges stimulates the Wolffian duct to develop into the epididymis, vas deferens, seminal vesicles and urethra
        
        testosterone also stimulates the development of the male external genitalia
      - development of female fetus
        
        requires no hormone control
        
        due to the absence of MIH, the Mullerian duct develops into the fallopian tubes, uterus, cervix and part of the vagina
        
        due no testosterone being present, the Wolffian duct regresses and the external female genitalia develop