Chapter 27: Pt. 2 Female Reproductive Flashcards
Female Development:
o First 5 weeks in utero, female cannot be distinguished from male.
o Female reproductive tract develops from the paramesonephric duct.
o Mesonephric duct degenerates… female reproductive organs and genitalia develop instead.
o All the oogonia (stem cells) a female will ever have are produced within the first 5 months of fetal life.
o At puberty (age 9 – 10 for most girls), there are only 250,000—400,000 primordial ovarian follicles left (still contain primary oocytes stuck in Prophase I of Meiosis I).
o Puberty is triggered by changes in the release of GnRH (Gonadotropin Releasing Hormone) from the hypothalamus, changing secretions from the anterior pituitary.
o FSH stimulates the development of several primordial follicles each month, causing them to release estrogen, progesterone, inhibin, and small amounts of androgens (testosterone-like hormones).
Female Oogonia:
o At the end of the 5th fetal month, each ovary contains about 3 million oogonia.
o Some differentiate into primary oocytes shortly before birth.
o Most primary oocytes undergo atresia before the baby girl is born, but the 1 - 2 million that are present at birth have already started Meiosis I and are “stuck” in Prophase I of Meiosis I.
o These primary oocytes are protected within a primordial ovarian follicle (surrounded by a single layer of follicular cells + basement membrane) and located within the cortex of the 2 ovaries.
Female Puberty:
o Puberty begins at age 9 – 10 years in US, but it is typically a 3 to 4 year process.
o Estrogens released during puberty have widespread effects on the female body:
• THELARCHE = onset of breast development.
• PUBARCHE = appearance of pubic and axillary hair/glands and sebaceous glands.
• MENARCHE = 1st menses (typically anovulatory 90% of time for first few years).
Age of Menarche:
o 1860: average age of menarche = 16.5 yrs.
o 1997: average age of menarche = 12 yrs.
o Menarche does not occur until a female has reached at least 17 and body fat.
o Female adult menstrual cycles usually cease (amenorrhea) if a woman drops below 22 and body fat (considered the minimum needed to allow for pregnancy and lactation).
o LEPTIN stimulates gonadotropin secretion (low body fat = low leptin levels = low FSH and LH that drive female menstrual cycle).
Menopause:
o “Climacteric” = change in hormones that accompanies menopause… usually begins when there are less than 1000 primary oocytes left.
o Menopause = permanent cessation of menses (female has gone entire year without a menstrual period).
o Typically occurs age 46 to 54 years (average age in US = 52 years).
o Menstrual periods become erratic and shorter in length.
o With fewer primary oocytes (estimated 3 – 1000 oocytes by age 50), less estrogen and progesterone are secreted, creates many signs and Symptoms:
o Hot flashes, mood swings, Headaches, insomnia, Hair loss, weight gain, Vaginal dryness, loss of bone mass, Atrophy of vagina, increase in s. cholesterol, Atrophy of uterus, in HDL cholesterol, Increase vaginal infections, increase in CVD risk.
Ovaries:
o Ovaries = female gonads
o Function:
o Produce female gametes (ova).
o Secrete hormones (progesterone, estrogens, inhibin).
o Gross Anatomy:
o Attached to broad ligament via the MESOVARIUM = peritoneal fold containing conduit for blood vessels.
o Ovarian ligament attaches ovary to uterus.
o Suspensory ligament attaches ovary to lateral pelvic wall (also conduit for blood vessels).
o Histology:
o Covered by germinal epithelium (simple cuboidal epithelial cells).
o Tunica albuginea just deep to germinal epithelium, surrounding the cortex.
o Ovarian cortex contains most of the primordial and developing follicles.
o Medulla of ovary contains larger blood vessels.
o The ovaries do not directly communicate with any other organs, release eggs into abdominopelvic cavity.
Oogenesis:
o Birth: 1 - 2 million primary oocytes stuck in Prophase I of Meiosis I. o Puberty: 250,000-400,000 primary oocytes left within primordial follicles of ovarian cortex. o Each month perhaps 8 to 20 primordial ovarian follicles begin to mature: o Primary ovarian follicles. o Secondary ovarian follicles o Graafian (vesicular) follicle —With an LH surge, primary oocyte finishes Meiosis I, follicle ruptures and ovum is ovulated, ovum (now a Secondary oocyte) becomes stuck in Metaphase II of Meiosis II (unless fertilized). o Developing follicles secrete primarily androgens which are converted to estrogen. o Graafian follicle expels egg into abdominopelvic cavity. o Differentiates into a corpus luteum, which cranks up production of both estrogen and progesterone (to prepare the uterus in case the ovum is fertilized)(also secretes inhibin). o If no uterine implantation, corpus luteum differentiates into a corpus albicans (scar tissue).
Fallopian Tubes (Uterine Tubes):
o 4” long canal that leads directly into uterus, also called the oviduct.
o 4 regions:
o Infundibulum.
o Ampulla (where fertilization normally occurs).
o Isthmus.
o Intramural region.
o Fimbriae of the infundibulum guide ovulated ovum into the Fallopian tube.
o Mucosa + muscularis + serosa.
Disorders of Fallopian Tube:
o PID = pelvic inflammatory disease:
o Infections from other parts of the reproductive tract (vaginal or uterine STDs) can travel backwards thru Fallopian tubes.
o Can cause scarring/fibrosis of tubes, resulting in infertility.
o Ectopic pregnancy:
o Implantation of developing embryo is “out of place”, can be fatal.
o Increased risk in women smokers.
Uterus:
o Located anterior to rectum and posterosuperior to urinary bladder.
o Normally, uterus is ANTEVERTED (tipped slightly anteriorly).
o Supported by 4 sets of ligaments:
o Broad ligaments.
o Round ligaments.
o Uterosacral ligaments.
o Cardinal ligaments.
Uterine Prolapse:
o 1st degree: cervix remains within vagina.
o 2nd degree: cervix protrudes thru vaginal orifice to exterior.
o 3rd degree: entire uterus is outside the vagina.
o Rx: pelvic exercises, pessary, surgery.
Regions of Uterus:
o Fundus. o Body. o Cervix. o Internal cervical os. o Cervical canal. o External cervical os. o Cervical Plug: Mucous barrier guarding entrance to cervix.
Cervical Plug:
o Cervical mucosa changes during the menstrual cycle, but doesn’t slough off.
o At ovulation (midpoint of cycle), the cervical glands secrete a thin SEROUS fluid that allows sperm to gain entry to the uterus from the vagina.
o At other times during the cycle, the secretions are so viscous they form a mucous plug, preventing the entry of both sperm and microorganisms.
Risk Factors for Cervical Cancer:
o First intercourse at an early age. o Multiple sexual partners. o Immunosuppression. o Cigarette smoking. o Poor nutrition. o Frequent cervical inflammations. o STDs, especially infections with human papillomavirus (HPV) leads to 75 to 80 percent of men and women are infected with HPV during their lifetime.
HPV Vaccines:
o Guardasil (2006) protects against HPV strains:
o 16, 18 (70 percent of cervical Ca).
o 6, 11 (90 percent of benign papillomas = “genital warts”).
o FDA approved males/females ages 9 to 26.
o CDC 2013 study: HPV targeted strains decrease 88 percent in vaccinated girls.
o Cervarix (2009) protects against HPV types:
o 16, 18 only.
o FDA approved only for females ages 10-25.
