Female Reproductive System: Anatomy and Functions

1. 27 P A R T B The Reproductive System

2. Female Reproductive Anatomy • Ovaries are the primary female reproductive organs • Make female gametes (ova) • Secrete female sex hormones (estrogen and progesterone) • Accessory ducts include uterine tubes, uterus, and vagina • Internal genitalia – ovaries and the internal ducts • External genitalia – external sex organs

3. Female Reproductive Anatomy Figure 27.11

4. The Ovaries • Paired organs on each side of the uterus held in place by several ligaments • Follicle Maturation: • At puberty, FSH initiates follicle maturation during which the follicle enlarges, follicular cells proliferate, and a fluid-filled cavity forms the secondary follicle

5. The Ovaries Figure 27.14a

6. Oogenesis • Production of female sex cells by meiosis • In the fetal period, oogonia (2n ovarian stem cells) multiply by mitosis and store nutrients • Primordial follicles appear as oogonia are transformed into primary oocytes • Primary oocytes begin meiosis but stall in prophase I

7. Oogenesis: Puberty • At puberty, one activated primary oocyte produces two haploid cells • The first polar body • The secondary oocyte • The secondary oocyte arrests in metaphase II and is ovulated • If penetrated by sperm the second oocyte completes meiosis II, yielding: • One large ovum (the functional gamete) • A tiny second polar body

8. Figure 27.19

9. Ovulation • Ovulation occurs when the ovary wall ruptures and expels the secondary oocyte • Mittelschmerz – a twinge of pain sometimes felt at ovulation • 1-2% of ovulations release more than one secondary oocyte, which if fertilized, results in fraternal twins

10. These images are the first time the event of ovulation in humans has been captured in clear detail. The yellow blob is a protruding egg cell, surrounded by supportive cumulus cells (at the black arrow). The reddish part is the follicle (S), and the pale pink tissue is part of the ovary (F).

11. Uterine Tubes (Fallopian Tubes) and Oviducts • Receive the ovulated oocyte and provide a site for fertilization • Empty into the uterus • Expand distally around the ovary forming the ampulla • The ampulla ends in the funnel-shaped, ciliated opening containing fingerlike projections called fimbriae

12. Uterine Tubes • The uterine tubes have no contact with the ovaries and the ovulated oocyte is cast into the peritoneal cavity • Beating cilia on the fimbriae create currents to carry the oocyte into the uterine tube • The oocyte is carried toward the uterus by peristalsis and ciliary action

13. Uterine Tubes • Nonciliated cells keep the oocyte and the sperm nourished and moist

14. Uterus • Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder • Body – major portion of the uterus • Fundus – rounded region superior to the entrance of the uterine tubes • Isthmus – narrowed region between the body and cervix

15. Uterus • Cervix – narrow neck which projects into the vagina inferiorly • Cervical canal – cavity of the cervix that communicates with: • The vagina via the external opening • The uterine body via the internal opening • Cervical glands secrete mucus that covers the external opening and blocks sperm entry except during midcycle

16. Vagina • Thin-walled tube lying between the bladder and the rectum, extending from the uterus to the exterior of the body • Partially covered by a membrane called the hymen. • Consists of three layers: the inner mucosal layers, a middle muscular layer and an outer fibrous layer. • Provides a passageway for birth, menstrual flow, and is the organ of copulation

17. Hormonal Control of Female Reproductive Funcitions • During childhood, ovaries grow and secrete small amounts of estrogens that inhibit the hypothalamic release of GnRH • As puberty nears, at about 10 years of age, GnRH is released; therefore FSH and LH are released by the pituitary, which act on the ovaries • These events continue until an adult cyclic pattern is achieved and menarche occurs

18. Female Sex Hormones • At puberty, the ovaries synthesize estrogen in response to FSH. • Estrogens are responsible for the female secondary sexual characteristics, such as breast development, increased adipose tissue deposition, and increased vascularization of the skin. • Ovaries also secrete progesterone, which triggers uterine changes during the menstrual cycle.

19. Uterine (Menstrual) Cycle • Series of cyclic changes that the uterine endometrium goes through each month in response to ovarian hormones in the blood • Days 1-5: Menstrual phase – uterus sheds all but the deepest part of the endometrium • Days 6-14: Proliferative (preovulatory) phase – endometrium rebuilds itself • Days 15-28: Secretory (postovulatory) phase – endometrium prepares for implantation of the embryo

20. Uterine (Menstrual) Cycle • A menstrual cycle is started by FSH, which stimulates the maturation of a follicle in the ovary. • Follicular cells surrounding the developing oocyte secrete estrogen, which is responsible for maintaining secondary sexual characteristics as well as the thickening of the uterine lining. • Ovulation is triggered by a mid-cycle surge in LH- Day 14. • Following ovulation, follicular cells turn into glandular corpus luteum that secretes increasing amounts of estrogen and progesterone.

21. Uterine (Menstrual) Cycle • If pregnancy does not occur, the corpus luteum degenerates, hormone levels decline, and the uterine lining disintegrates and is shed. • During the cycle, estrogen and progesterone inhibit the increased release of FSH and LH; when estrogen and progesterone levels fall, the secretion of FSH and LH increases. • Days 26-28 – decline of the ovarian hormones • Ends the blockade of FSH and LH • The cycle starts anew • If pregnancy does occur, the corpus luteum produces hormones until the placenta takes over that role (at about 3 months)

22. Animated Menstrual Cycle • MSNBC interactive

26. Menopause • Menstrual cycles continue throughout middle age until menopause, when the cycles cease. • The cause of menopause is the aging of the ovaries when follicles no longer mature and estrogen levels decline

27. Birth Control • Voluntary regulation of the number of offspring produced, requiring the use of contraception • Coitus Interruptus: • Withdrawl of the penis prior to ejaculation, preventing entry of sperm into the female reproductive tract. • This method may be difficult for the male to carry out, and since some sperm cells are present in the secretions of the penis prior to ejaculation, this method might lead to preganancy

28. Birth Control • Rhythm Method: • Requires abstinence from intercourse during the days of the month in which the female is fertile. • The accurate determination of the days when the female is fertile is sometimes difficult. Chemical Barriers: Spermicides in the form of creams, foams, and jellies They are more effective when used with a diaphragm.

29. Birth Control • Oral Contraceptives: • Birth control pills contain estrogen-like and progesterone-like substances that disrupt the normal cycle of hormones and prevent ovulation. • If used correctly, they are nearly 100% effective, but may have side effects in some people.

30. Birth Control • Injectable Contraception: • An intramuscular injection of Depo-Provera can suppress the release of a secondary oocyte for up to 3 months. • Side effects occur in some people, and this method of birth control may not be suitable for many women.

31. Birth Control • Contraceptive Implants: • A set of small progesterone-containing capsules or rods inserted surgically under the skin. • May be effective for up to 5 years. Intrauterine Devices: IUD is a small, solid object inserted into the uterine cavity that interferes with implantation Serious health problems have been reported with their use.

32. Birth Control • Surgical Methods: • Sterilization includes vasectomy (severing the vasa deferntia) in males and tubal ligation (severing the uterine tubes) in females. • These provide the most reliable methods of birth control and may be reversible using microsurgery.

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34. Sexually Transmitted Diseases • There are 20 recognized sexually transmitted diseases (STDs), which are often silent or go unnoticed, especially in females. • One possible complication of the STDs gonorrhea and chlamydia is pelvic inflammatory disease, which may lead to infection and sterility in females. • Acquired Immune Deficiency Syndrome (AIDS) is a sexually transmitted disease most frequently transmitted during unprotected intercourse or by sharing needles.

35. Mammary Glands • Modified sweat glands consisting of 15-25 lobes that radiate around and open at the nipple • Accessory organs of the female reproductive system that are specialized to produce and secrete milk after pregnancy. • Areola – pigmented skin surrounding the nipple • Suspensory ligaments attach the breast to underlying muscle fascia • Lobes contain glandular alveoli that produce milk in lactating women • Compound alveolar glands pass milk to lactiferous ducts, which open to the outside

36. Structure of Lactating Mammary Glands Figure 27.17

37. Breast Cancer • Usually arises from the epithelial cells of the ducts • Risk factors include: • Early onset of menses or late menopause • No pregnancies or the first pregnancy late in life • Previous history of breast cancer or family history of breast cancer • Hereditary factors including mutations to the genes BRCA1 and BRCA2 • 70% of women with breast cancer have no known risk factors

38. Breast Cancer: Detection and Treatment • Early detection is by self-examination and mammography • Treatment depends upon the characteristics of the lesion • Radiation, chemotherapy, and surgery followed by irradiation and chemotherapy • Today, lumpectomy is the surgery used rather than radical mastectomy