1. Mammalian Reproductive Systems
Period 1

2. Female Reproductive System
AP Book
IB Book

3. Female Reproductive Anatomy
The female’s external reproductive structures are the clitoris and the two sets of labia that surround the clitoris and the vaginal opening
The internal organs are the pair of gonads (ovaries) and the chambers that carry gametes (oviducts) and house the embryo and fetus (uterus).

4. Ovaries Lie in the abdominal cavity, attached to the uterus
Each ovary is enclosed in a protective capsule and contains many follicles.
A follicle consists of an egg surrounded by at least one layer of follicle cells which nourish and protect the developing egg cell.
Only a few hundred of the 400,000 follicles will release egg cells during a female’s reproductive years.

5. Ovaries Cont.
The cells of the follicle produce estrogens, the primary female sex hormones.
Ovulation is when an egg cell is expelled from the follicle.
The remaining follicle tissue grows and forms a solid mass called the corpus luteum (“yellow body”).
The corpus luteum secretes additional estrogens and progesterone, the hormone that helps maintain the uterine lining during pregnancy.
Corpus luteum disintegrates if the egg cell is not fertilized.

6. Oviducts
During ovulation, the egg cell is released into the abdominal cavity near the opening of the oviduct (fallopian tube).
Cilia on the epithelium lining of the duct help collect the cell by drawing fluid from the body cavity into the duct and carrying the cell through the duct to the uterus

7. Uterus
A thick, muscular organ that can expand during pregnancy to accommodate a 4-kg fetus.
The endometrium (the inner lining of the uterus) is richly supplied with blood vessels.
The cervix is the neck of the uterus which opens into the vagina.

8. Vagina and Vulva
The vagina is a thin-walled chamber that is the repository for sperm during copulation and serves as the birth canal.
The vagina opens to the outside at the vulva.
The vulva is the collective term for the external female genitalia.

9. Vulva
The hymen is a thin piece of tissue that partially covers the vaginal opening until sexual intercourse or vigorous physical activity ruptures it.
The vaginal opening and the separate urethral opening are located in a recess called the vestibule, bordered by a pair of slender skin folds, the labia minora.
The labia majora (a pair of thick, fatty ridges) encloses and protects the labia minora and the vestibule.

10. Vulva Cont. The clitoris is located at the front of the vestibule.
It consists of a short shaft supporting a rounded glans (head) covered by a small hood of skin, the prepuce.
During sexual arousal, the clitoris, the vagina and the labia minora engorge with blood.
Because the clitoris is mostly erectile tissue, it is richly supplied with nerve endings and, therefore, one of the most sensitive point of sexual stimulation.
Bartholin’s glands secrete mucus into the vestibule during sexual arousal to keep it lubricated and facilitate intercourse.

11. Mammory Glands Present in both sexes but function only in women.
NOT PART OF THE REPRODUCTIVE SYSTEM—But important to mammalian reproduction.
Within glands, small sacs of epithelial tissue secrete milk, which drains into a series of ducts opening at the nipple.
Fatty (adipose) tissue forms the main mass of the mammary gland of a non-lactating mammal.
Males do not develop the secretory apparatus or fatty deposits because of low estrogen levels.

12. Male Reproductive System
AP Book
IB Book

13. Testes
The male gonads that consist of many highly coiled tubes (seminiferous tubules) surrounded by several layers of connective tissue.
Seminiferous tubules are where sperm form.
The Leydig cells scattered between the seminiferous tubules produce testosterone and other androgens.
The testes of many animals are held outside the body in the scrotum (a fold of the body wall 2°C below the rest of the body) because the production of normal sperm cannot take place at the body temperature of most animals.

14. Ducts
From the seminiferous tubule of a testis, the sperm pass into the coiled tubules of the epididymis. (Passage of the sperm through the 6-m epididymis takes ~20 days.)
During the passage, the sperm become motile and able to fertilize an egg.
During ejaculation, sperm is propelled from the epididymis through the vas deferens (ductus deferens in the AP picture and sperm duct in IB picture), one from each epididymis.

15. Ducts Cont.
Each vans deferens runs around the scrotum and behind the urinary bladder, joining a duct from the seminal vesicle and forming the ejaculatory duct.
The ejaculatory duct opens into the urethra, the tube that drains both the excretory system and the reproductive system.
The urethra runs through the penis and opens to the outside.

16. Glands
Three sets of accessory glands add secretions to the semen, the fluid that is ejaculated.
Seminal vesicles
Contributes about 60% of the total volume of semen
The fluid from the seminal vesicles is thick, yellowish and alkaline.
Fluid contains mucus, sugar fructose (energy for sperm), coagulating enzyme, ascorbic acid and prostaglandins (local regulators)

17. Glands Cont. Prostate Gland Largest of the semen-secreting glands
Secretes thin, milky prostatic fluid directly into the urethra through several small ducts
Benign enlargement of the prostate occurs in more than half of men over 40.
Prostate cancer is one of the most common cancers in men.

18. Glands Cont. Bulbourethal Glands
A pair of small glands along the urethra below the prostate
Secrete a clear mucus that neutralizes and acidic urine remaining in the urethra before ejaculation.
Carries some sperm released before ejaculation hence the EPIC FAIL of the coitus interruptus method of contraception.

19. Semen in the Female Reproductive Tract
A man ejaculates 2-5mL of semen (1 mL of semen = ~ million sperm)
Inside the female tract, prostaglandins cause thinning of the mucus at the opening of the uterus, stimulating uterine muscle contractions that help move the semen.
Alkalinity of semen neutralizes the acidic environment of vagina
First, semen coagulates for uterine muscle contractions; then, anticoagulants liquefy semen to allow sperm mobility.

20. Penis
Composed of 3 cylinders of spongy erectile tissue derived from modified veins and capillaries.
During sexual arousal, tissue fills with blood from arteries and veins are sealed off, resulting in an erection.
An erection is essential to insertion of the penis into the vagina (Exceptions include rodents, raccoons, walruses, whales and some other mammals that have a baculum, a bone that is contained in and helps stiffen the penis

21. Penis Cont.
The main shaft of the penis is covered by relatively thick skin.
The head (glans penis) has a much thinner covering and is more sensitive to stimulation.
The human glans is covered by a fold of skin called the foreskin (prepuce) which may be removed by circumcision.

22. A Little Extra…
Human Sexual Response: Two types of physiological reactions in both sexes  vasocongestion (the filling tissue with blood) and myotonia (increased muscle tension)
Phase 1: Excitement
Preparation of the vagina and penis for coitus (sexual intercourse)
Evident from erection of the penis and clitoris; enlargement of the testes, labia and breasts; and vaginal lubrication

23. Human Sexual Response Cont.
Phase 2: Plateau
Vasocongestion of the outer third of the vagina and elevation of the uterus forms a depression to receive sperm at the back of the vagina.
Breathing increases and heart rate rises because of an involuntary response to stimulation.
Phase 3:Orgasm
Rhythmic, involuntary contractions of the reproductive structures in both sexes
Male orgasm has two stages: Emission (the contraction of the glands and ducts that force semen into the urethra) and Expulsion/Ejaculation (when the urethra contracts and the semen is expelled.

24. Human Sexual Response Cont.
During female orgasm, the uterus and outer vagina contract but the inner two-thirds of the vagina do not.
Orgasm is the shortest phase of the sexual response cycle.
Phase 4: Resolution
Reverses the responses of the earlier stages
Vasocongested organs return to their normal size and color.
Muscles relax.
Most changes of resolution are completed in 5 minutes, but loss of penile and clitoral erection may take longer.

25. Mini-Quiz!
For the Girls…
For the Boys…