1. The Reproductive System
Chapter 27
The Reproductive System
Part C

2. lies between the bladder and the rectum
Vagina
Thin-walled tube
lies between the bladder and the rectum
Extends from the cervix to the exterior of the body
The urethra is embedded in its the anterior wall
Provides a passageway for:
Copulation
Birth
Menstrual flow

3. Wall consists of three coats:
Vagina
Wall consists of three coats:
Fibroelastic adventitia
Smooth muscle muscularis
Stratified squamous mucosa
Hymen:
Incomplete mucosal partition near the vaginal orifice
Vaginal fornix:
Upper end of the vagina surrounding the cervix

4. Vagina
Figure 27.16a

5. Female External Genitalia: Deep
Figure 27.16b

6. External Genitalia: Vulva (Pudendum)
Lies external to the vagina and includes:
Mons pubis:
Round, fatty area overlying the pubic symphysis
Labia majora
Elongated, hair-covered, fatty skin folds
Homologous to the male scrotum
Labia minora
Hair-free skin folds lying within the labia majora
homologous to the spongy/penile urethra

7. External Genitalia: Vulva (Pudendum)
Greater vestibular glands:
Pea-size glands flanking the vagina
Homologous to the male bulbourethral glands
Keep the vestibule moist and lubricated
Clitoris:
homologous to the penis
Erectile tissue hooded by the prepuce
The exposed portion is called the glans
Has corpora cavernosa (no spongiosum) tissue
Perineum:
Diamond-shaped region between the pubic arch and coccyx
Bordered by the ischial tuberosities laterally

8. Mammary Glands Modified sweat glands Consist of 15-25 lobes
Lobes are radiating around and open at the nipple
Areola is the pigmented skin surrounding the nipple
Suspensory ligaments attach breast to underlying muscle fascia
Lobes contain glandular alveoli that produce milk in lactating women
Compound alveolar glands pass milk to lactiferous ducts
Lactiferous ducts open to the outside

9. Structure of Lactating Mammary Glands
Figure 27.17

10. 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

11. Oogenesis Is the production of female sex cells by meiosis
In the fetal period, oogonia (2n stem cells) multiply by mitosis
They enter growth phase and store nutrients
Primordial follicles (immture oocyte surrounded by a single squamous follicle cells layer, 2n)
They transform into primary oocytes (with single cuboidal or columnar follicle cell layer, 2n)
Primary oocytes begin meiosis but arrests in prophase I until puberty
Meiosis I takes years to complete

12. Oogenesis: Puberty
At birth a female has her lifetime supply of primary oocytes
At puberty, an activated primary oocyte produces two dissimilar haploid cells:
The smaller one is called the first polar body
The 2nd larger one is the secondary oocyte
The secondary oocyte arrests in metaphase II and is ovulated
If the 2ndary oocyte is penetrated by sperm it completes meiosis II, again yielding dissimilar cells:
One large ovum, the functional gamete
A tiny 2nd polar body

13. Figure 27.19

14. Ovarian Cycle
Monthly series of events associated with the maturation of an egg
Follicular phase – period of follicle growth (days 1–14)
Luteal phase – period of corpus luteum activity (days 14–28)
Ovulation occurs midcycle

15. Primary follicle becomes a secondary follicle
Follicular Phase
The primordial follicle, directed by the oocyte, becomes a primary follicle (cuboidal cells & growth)
Primary follicle becomes a secondary follicle
A layer of connective tissue (theca folliculi) form around the follicle
The theca folliculi and granulosa cells cooperate to produce estrogens (theca androgen converted by granulosa to E2)
The zona pellucida forms by & around the oocyte
The fluid-filled cavity called antrum is formed

16. The secondary follicle becomes a vesicular follicle
Follicular Phase
The secondary follicle becomes a vesicular follicle
The antrum expands isolating the oocyte and its surrounding cells called the corona radiata
The full size follicle (vesicular follicle) bulges from the external surface of the ovary
The primary oocyte completes meiosis I, and the stage is set for ovulation
Unlike the luteal phase, the follicular phase may vary in length (21-40 days)

17. Ovarian Cycle
Figure 27.20

18. Ovulation
Ovulation occurs when the ovary wall ruptures
LH hormone surge is the stimulus
Secondary oocyte with its corona radiata is expelled
A twinge of pain (Mittelschmerz) sometimes felt
1-2% of ovulations release more than one secondary oocyte, which if fertilized, results in fraternal twins

19. Luteal Phase
After ovulation, the ruptured follicle collapses
Granulosa cells enlarge, and along with internal thecal cells, form the corpus luteum
The corpus luteum secretes progesterone and estrogen
If pregnancy does not occur, the corpus luteum degenerates in 10 days, leaving a scar (corpus albicans)
If pregnancy does occur, the corpus luteum produces hormones until the placenta takes over that role (at about 3 months)

20. Establishing the Ovarian Cycle
During childhood:
Ovaries grow and secrete small amounts of estrogens
Secreted E2 inhibits the hypothalamic release of GnRH
As puberty nears:
GnRH is released by the hypothalamus
FSH & LH are released by the pituitary; they act on the ovaries
These events continue until an adult cyclic pattern is achieved and menarche occurs

21. Hormonal Interactions During the Ovarian Cycle
Day 1 – GnRH stimulates the release of FSH & LH
FSH and LH stimulate follicle growth & maturation, and low-level estrogen release
Rising estrogen levels:
Inhibit the release of FSH and LH
Prod the pituitary to synthesize and accumulate these gonadotropins

22. Hormonal Interactions During the Ovarian Cycle
Estrogen levels increase
High estrogen levels have a positive feedback effect on the pituitary
This causes a sudden surge of LH

23. Hormonal Interactions During the Ovarian Cycle
The LH spike stimulates the primary oocyte to complete meiosis I
The secondary oocyte continues on to metaphase II
Day 14 – LH triggers ovulation
LH transforms the ruptured follicle into a corpus luteum (CL)
The CL produces inhibin, progesterone, and estrogen

24. Hormonal Interactions During the Ovarian Cycle
These hormones shut off FSH and LH release
The declining LH ends luteal activity
Days 26-28: The decline of the ovarian hormones
Ends the blockade of FSH and LH
The cycle starts anew

25. Feedback Mechanisms in Ovarian Function
Figure 27.21

26. Uterine (Menstrual) Cycle
A series of monthly cyclic uterine endometrial changes
they occur in response to ovarian hormones in the blood
Menstrual phase (Days 1-5):
Uterus sheds all but the deepest part of the endometrium
Proliferative (preovulatory) phase (Days 6-14):
Endometrium rebuilds itself
Secretory (postovulatory) phase (Days 15-28):
Endometrium prepares for implantation of the embryo

27. Menses If fertilization does not occur: Spiral arteries:
Progesterone levels fall
Endometrium is deprived of hormonal support
Spiral arteries:
kink and go into spasms
Endometrial cells begin to die
Functional layer:
Begins to digest itself
Constrict one final time
Then suddenly relax & open wide
Blood rushes, fragmenting weakened capillary beds
The functional layer sloughs

28. Uterine Wall
Figure 27.15b

29. Gonadotropins, Hormones, and the Ovarian and Uterine Cycles
Figure 27.22a, b

30. Gonadotropins, Hormones, and the Ovarian and Uterine Cycles
Figure 27.22c, d

31. Extrauterine Effects of Estrogens and Progesterone
Estrogen levels rise during puberty
Promote oogenesis and follicle growth in the ovary
Exert anabolic effects on the female reproductive tract
Uterine tubes, uterus, and vagina grow larger and become functional
Uterine tubes and uterus exhibit enhanced motility
Vaginal mucosa thickens
External genitalia mature

32. Estrogen-Induced Secondary Sex Characteristics
Growth of the breasts
Increased deposition of subcutaneous fat, especially in the hips and breasts
Widening and lightening of the pelvis
Growth of axillary and pubic hair

33. Female Sexual Response
The clitoris, vaginal mucosa, and breasts engorge with blood
Activity of vestibular glands lubricates the vestibule and facilitates entry of the penis
Orgasm:
Accompanied by muscle tension
Increase in pulse rate and blood pressure
Increase in rhythmical contractions of the uterus

34. Female Sexual Response
Unlike males, females:
Do not have a refractory period after orgasm
Can experience multiple orgasms in a single sexual experience
Orgasm is not essential for conception

35. Ovulation and menses cease entirely Without sufficient estrogen:
Menopause
Ovulation and menses cease entirely
Without sufficient estrogen:
Reproductive organs and breasts atrophy
Irritability and depression result
Skin blood vessels undergo intense vasodilation (hot flashes )
Gradual thinning of the skin
Bone loss
Males have no equivalence to menopause