Anatomy and Physiology 2 Chapter 28 - Spermatogenesis and Female Reproductive System

spermatogenesis

spermatogenic cells give rise to sperm; takes 64-72 days if conditions are hospitable

• mitosis = spermatogonia > primary spermatocytes

• meiosis = primary spermatocytes > secondary spermatocytes > spermatids

• spermiogenesis = spermatids > spermatozoa (sperm)

3 steps of spermatogenesis

1. mitosis: spermatogonia are stem cells in the seminiferous tubules that undergo cell division throughout adult life, some differentiate into primary spermatocytes, which prepare to begin meiosis

2. meiosis I and II: primary spermatocytes undergo meiotic divisions that produce spermatids, undifferentiated male gametes

3. spermiogenesis: spermatids differentiate into physically mature sperm

3 parts of sperm anatomy

1. head: genetic region, nucleus and helmet-like acrosome containing hydrolytic enzymes that enable sperm to penetrate egg

2. midpiece: metabolic region, mitochondria make ATP to move tail

3. tail: locomotor region, flagellum

3 things about sperm maturation and capacitation

• changes to cell surface proteins in the epididymis and gain of motility

• surface proteins coated by seminal plasma during ejaculation

• capacitation: occurs in female reproductive tract

  • hyperactive motility

  • enables sperm to bind ovulated egg

what is the hormonal pathway of LH and its affects on the body for males

release of GnRH > secretion of LH > interstitial cells > secretion of testosterone > effects on CNS, stimulation of bone and muscle growth, establish and maintain male secondary sex characteristics, and maintain accessory glands and organs

*secretion of testosterone can also impact nurse cells

*testosterone is a negative feedback to GnRH

what is the hormonal pathway of FSH and its affects on the body for males

release of GnRH > secretion of FSH > seminiferous tubules > nurse cells > synthesis of androgen-binding proteins (ABP) and stimulation of spermatogenesis and spermiogenesis

*nurse cells can lead to secretion of inhibin, causing a negative feedback to secretion of FSH

ovaries

female gonads that do the following:

• produce immature female gametes

• secrete female sex hormones: estrogen (estradiol, estrone, and estriol) and progesterone

• secrete inhibin for negative feedback on FSH

3 ligaments that support the ovaries

1. ovarian ligament: anchors ovary medially to uterus

2. suspensory ligament: anchors ovary laterally to pelvic wall

3. broad ligament: supports uterine tubes, uterus, and vagina

what are the 2 regions of the ovary

1. outer cortex: houses forming gametes

2. inner medulla: large blood vessels and nerves

*regions are poorly defined

3 accessory ducts of the female reproductive system

1. uterine tubes

2. uterus

3. vagina

uterine tube (fallopian tubes or oviduct)

receives ovulated oocyte, usually site of fertilization; ducts have no physical contact with ovary (oocyte cast into peritoneal cavity

4 regions of the uterine tube in order

1. fimbriae: fingerlike projections that create a current to draw oocyte into uterine tube

2. infundibulum: lined with cilia that beat toward middle region of the uterine tube

3. ampulla: site of fertilization

4. isthmus: constricted region where tube joins the uterus

3 tissue of the uterine tube

1. serosa: outermost

2. muscularis

3. mucosa: innermost

ectopic pregnancy

oocyte fertilized in peritoneal cavity or distal uterine tube begins developing there; normally abort naturally with substantial bleeding and mostly occurs in the fallopian tube

uterus

hollow, thick walled, muscular organ that receives, retains, and nourishes fertilized ovum

6 parts of the uterus (gross anatomy)

1. isthmus: narrowed inferior region

2. fundus: rounded superior region

3. body: major portion

4. cervical canal: communicates with cervical glands

5. cervical glands: secrete mucus that blocks sperm entry except during midcycle

6. cervix: narrow neck or outlet, projects into vagina

cervical cancer

• most common between 30-50 years old

• risks: frequent cervical inflammations, STIs, multiple pregnancies

• pap smear for detection: every 2 years (21-30 years old), every year (>30 years old), stopped after 65 years old if negative for 10 years

3 layers of the uterine wall

1. perimetrium: serous layer, outermost layer

2. myometrium: interlacing layers of smooth muscle

3. endometrium: mucosal lining, innermost layer

   1. basal layer: stays relatively consistent via uterine cycle

   2. functional layer: changes in response to ovarian hormone cycles, shed during menstruation

vagina

birth canal and organ that receives penis during intercourse, passage to eliminate menstrual fluids

gross anatomy of the vagina

• thin-walled tube 8-10 cm in length

• extends between bladder and rectum from cervix to exterior

• urethra parallels course anteriorly; embedded in anterior wall

5 things on the histology of the vagina

• lumen of vaginal canal

• stratified squamous epithelium

• lamina propria

• blood vessels

• smooth muscle fibers

external genitalia (vulva = area)

vagina opens to vestibule bordered by external genitalia, urethral opening anterior to vaginal opening

3 parts of the external genitalia

1. labia minora and majora: small hairless folds surrounding vestibule (minora), outer margins of the vulva (majora)

2. clitoris: small tissue projection derived from same embryonic structures of penis, corpus cavernosum engorges with blood during arousal, prepuce formed by labia minora

3. greater vestibular glands: flank vaginal opening, homologous to bulbo-urethral glands, release mucus into vestibule for lubrication

3 things about female sexual function

• coordination between both branches of ANS

• orgasm associated with intensely pleasurable sensation accompanied by contractions of uterine and vaginal walls > no resolution and refractory period

• parasympathetic

  • relaxation of arterial walls leading to vessel dilation > increased blood flow to clitoris and vestibular bulbs and increased secretions from cervical and greater vestibular glands

  • blood vessels of vaginal wall dilate and blood flow increase > fluid pushed from connective tissue to surface of epithelium

breasts and its anatomy

• modified sweat glands consisting of 15-25 lobes and help in the production of milk

• areola: pigmented skin surrounding nipple

• lobules within lobes contain alveoli that produce milk

breast cancer

• most common malignancy that usually arises from epithelial cells of smallest ducts that eventually metastasize

• risk factors: early onset menstruation and late menopause, no pregnancies or first is late in life, no or short periods of breast feeding, and family history

oogenesis

• production of female gametes

  • takes years to complete

• begins in fetal period

  • oogonia (2n stem cells) multiply by mitosis and store nutrients

  • primary oocytes develop in primordial follicles > being meiosis and stall in prophase I

4 steps of oogenesis

• begins in fetal period

  • oogonia (2n stem cells) multiply by mitosis and store nutrients

  • primary oocytes develop in primordial follicles > being meiosis and stall in prophase I

• each month after puberty, a few primary oocytes activated

  • one each month resumes meiosis I

    • results in 2 haploid cells of different sizes

    • secondary oocyte: large cell with all cytoplasm and organelles of original cell

    • first polar body: small cell

• secondary oocyte arrests in metaphase II; ovulated ovum

• if not penetrated by sperm, secondary oocyte deteriorates

• if penetrated by sperm, secondary oocyte completes meiosis II yielding: ovum (functional gamete) and 3 polar bodies

oogenesis vs. spermatogenesis

spermatogenesis:

• 4 viable sperm

• error rate of 3-4%

oogenesis:

• 1 viable ovum, 3 polar bodies

• error rate of 20%