Female Reproductive System

Female Reproductive System

• The female reproductive system consists of:
  • Gonads (ovaries) that produce secondary oocytes and hormones
  • Uterine (fallopian) tubes or oviducts that transport fertilized ova
  • Uterus where fetal development occurs
  • Vagina
  • External organs (vulva or pudendum)
  • Mammary glands that produce milk

Ovaries

• Paired glands homologous to the testes
• Produce:
  • Gametes (secondary oocytes that develop into mature ova/eggs after fertilization)
  • Hormones (progesterone, estrogens, inhibin, and relaxin)

Ovarian Ligaments

• Series of ligaments that hold ovaries in place:
  • Broad ligament (a fold of parietal peritoneum)
  • Ovarian ligament (anchors ovaries to uterus)
  • Suspensory ligament (attaches ovaries to pelvic wall)

Histology of Ovary

• Germinal epithelium covers the surface of the ovary
• Tunica albuginea is located underneath the epithelium
• Ovarian cortex contains:
  • Ovarian follicles and stromal cells
• Ovarian medulla contains:
  • Blood vessels, lymphatic vessels, and nerves

Ovarian Follicles

• In the cortex and consist of oocytes in various stages of development
• Mature (graafian) follicle is a large, fluid-filled follicle ready to expel a secondary oocyte during ovulation
• Corpus luteum is the remnant of a mature follicle after ovulation

Oogenesis and Follicular Development

• Results in the formation of a single haploid secondary oocyte
• During early fetal development, primordial germ cells migrate from the yolk sac to the ovaries and differentiate into oogonia (diploid stem cells)
• Before birth, most germ cells degenerate (atresia), while a few develop into primary oocytes that enter meiosis I during fetal development
• Each primary oocyte is covered by a single layer of flat follicular cells (primordial follicle)
• Around 200,000-2,000,000 primordial follicles are present at birth in each ovary, with 40,000 remaining at puberty and around 400 maturing and ovulating during a lifetime

Follicular Development

• Each month from puberty to menopause, FSH and LH stimulate the development of several primordial follicles (one reaches ovulation)
• Just before ovulation, a diploid primary oocyte completes meiosis I, producing two unequal-sized haploid cells (secondary oocyte and first polar body)
• At ovulation, the secondary oocyte is expelled with the first polar body
• If fertilization does not occur, the cells degenerate
• If a sperm penetrates the secondary oocyte, meiosis II resumes, and the secondary oocyte splits into two unequal-sized cells (second polar body and ovum or mature egg)

Functions

• Transport of spermatozoa, menstruation, implantation of fertilized ovum, development of fetus during pregnancy, and labor

Anatomically

• Can be subdivided into:
  • Fundus
  • Body
  • Isthmus
  • Cervix (opens into vagina)

Uterine (Fallopian) Tubes or Oviducts

• Provide a route for sperm to reach an ovum
• Site of fertilization
• Transport secondary oocytes and fertilized ova from ovaries to uterus
• Consist of:
  • Infundibulum (ends in finger-like fimbriae)
  • Ampulla (widest, longest portion)
  • Isthmus (joins uterus)

Histology of Uterine Tubes

• Three layers:
  1. Mucosa (ciliary conveyor belt, peg cells provide nutrition to ovum)
  2. Muscularis (peristaltic contractions)
  3. Serosa (outer layer)

Histology of the Uterus

• Three layers:
  1. Perimetrium (outer layer)
  2. Myometrium (three layers of smooth muscle contractions in response to oxytocin)
  3. Endometrium (inner layer, highly vascularized)

Stratum Functionalism

• Lines the cavity and sloughs off during menstruation

Stratum Basalis

• Permanent layer that gives rise to new stratum functionalis after each menstruation

Blood Supply of the Uterus

• Uterine arteries branch into:
  • Arcuate arteries
  • Radial arteries that supply the myometrium
• Straight and spiral branches penetrate to the endometrium
  • Spiral arteries supply the stratum functionalis
  • Their constriction due to hormonal changes starts the menstrual cycle

Secretions and Functions

• Cervical mucus (a mixture of water, glycoprotein, serum-type proteins, lipids, enzymes, and inorganic salts)
  • When thin, it is more receptive to sperm
  • When thick, it forms a cervical plug that physically impedes sperm penetration
  • Supplements the energy needs of sperm
• Cervix and mucus also play a role in capacitation, rendering sperm competent to fertilize an oocyte

Vagina

• Fibromuscular canal extending from the exterior of the body to the uterine cervix
• Mucosa continuous with uterine mucosa
  • Decomposition of glycogen makes an acidic environment hostile to microbes and sperm
  • Alkaline components of semen raise pH
• Functions as a passageway for spermatozoa and menstrual flow
• Also the receptacle of the penis during sexual intercourse and the lower portion of the birth canal

Vulva or Pudendum (External Female Genitalia)

• Mons pubis (fatty pad cushions pubic symphysis)
• Labia majora (homologous to scrotum)
• Labia minora (homologous to spongy urethra)
• Clitoris (small mass of erectile tissue and numerous nerves/blood vessels, homologous to glans penis)
• Vestibule (region between labia minora)
• Bulb of the vestibule (2 elongated masses of erectile tissue on either side of vaginal orifice)

Perineum

• Diamond-shaped area medial to thighs and buttocks in both males and females
• Contains external genitalia and anus
• During childbirth, the emerging fetus may cause excessive stretching and tearing of the perineum

Mammary Glands

• Modified sudoriferous glands that produce milk (lactation)
  • 15-20 lobes divided into lobules composed of alveoli (milk-secreting glands)
• Milk-secreting glands open by lactiferous ducts at the nipple
• Areola (pigmented area surrounding the nipple)

The Female Reproductive Cycle

• Encompasses ovarian and uterine cycles, hormonal changes that regulate them, and related changes in breast and cervix
• Controlled by the monthly hormone cycle of the anterior pituitary, hypothalamus, and ovary

This quiz covers the components and functions of the female reproductive system, including ovaries, uterine tubes, uterus, vagina, and external organs. It also explains the role of ovaries in producing gametes and hormones.