1. The Reproductive
System

2. Major Functions of the Reproductive System
To generate haploid gametes in the testes/ovaries
To facilitate fertilization in the uterus
To nourish the growth and development of the zygote in the uterus

3. The “Haploid” Condition
Meiosis results in the production of haploid gametes (sex cells) which have only 23 chromosomes.
Meiosis involves two divisions, meiosis I and meiosis II.
By the end of meiosis II, the diploid cell that entered meiosis has become 4 genetically different haploid cells (N).

5. Gamete Development…
Spermatogenesis: four new cells from meiosis called spermatids in males develop into mature sperm cells

6. Gamete Development (cont.)
Oogenesis: During cytokinesis following meiosis in females, cytoplasm is divided unequally among the four new cells.
One cell receives most of the original cell’s cytoplasm and develops into a mature egg called an ovum. The other three cells called polar bodies die off.

7. Gamete Development (cont.)

8. Sexual Reproduction
When the nuclei of the two gametes combine during fertilization, the 2n number is restored (2n = 46).
The fusion of two gametes produces the first cell of the new animal called a zygote.

9. “OMG! A zygote?...
How romantic!”
“I want one of my haploid gametes to fertilize one of your haploid gametes…”

10. Anatomy of the Male

11. Anatomy of the Male: the Prostate
Prostate: A chestnut-like gland found below the bladder that completely surrounds the urethra. This gland produces a thin fluid that neutralizes the pH of the urethra and enables the sperm to pass through the urethra without harm.

12. The Cowper’s Glands
approximately the size of a pea, males have 2 Cowper’s Glands located just lateral to the prostate.
During sexual arousal these glands secrete a clear, viscous fluid known as pre-ejaculate. This fluid helps to lubricate the urethra for spermatozoa to easily pass, while also neutralizing traces of acidic urine in urethra

13. Anatomy of the Male: the Epididymis
Epididymis: A tightly coiled, tubular mass that carries sperm from the testes to the vas deferens. Sperm collect here and finalize their development before their journey to the vas deferens.

15. Anatomy of the Male: The Vas Deferens and the Urethra
Urethra: The tube that carries semen from the ejaculatory duct to the outside of the body. In males, the urethra also carries urine from the bladder.
Vas deferens: The tube on opposite sides of the scrotum which carry sperm from the epididymis to the ejaculatory duct (connected to the urethra).

16. Seminal Fluid: A Closer Look
Semen contains the following components from the following sources:
Testes (2-5%) million haploid sperm cells
Seminal Vesicles: (65-75%)- Amino Acids, citric acid, fructose, prostoglandins
Prostate gland (20-25%)- immunosupressing enzymes, prostatic acid, prostate-specific antigen, Zinc
Cowper's Glands (less than 1%)- Alkaline Mucus

17. Anatomy of the Male: Seminal Vesicles
Seminal vesicles: A pair of glands located on opposite sides of the bladder. These glands discharge seminal fluid that becomes the main component of semen. Seminal fluid nourishes the sperm and helps it move through the urethra.

18. Anatomy of the Male: Testes and Scrotum
Testes: egg-shaped male reproductive glands that secrete the male sex hormone testosterone and produce sperm. The testes are also called the testicles.
Scrotum: The external sac of skin that holds the testes.

19. Specialized Cells within the Testes
Within the lumen of the seminerfeous tubules, spermatgonial germ cells generate spermatids. This process takes days.
Mature sperm are nourished by Sertoli cells before they journey to the epididymis where they can be stored for days. These cells must be activated by FSH, and secrete Inhibin to close the negative feedback loop.
Interstitial cells within the tubules generate testosterone. This is triggered by LH, and inhibited by Sertoli cells (see above).

20. The Testes: A Closer Look
Within the testes, the coiled semeniferous tubules (approximately 20 meters in length) contain specialized cells which generate both sperm and hormones.

21. Testes Histology

23. Challenge Question!
What is a “Vasectomy? Be Specific

24. The Male Gamete: Sperm
Sperm production begins at puberty and continues until death, with hundreds of millions of sperm being produced each day!
Once formed, sperm move into the epididymis, where they mature and are stored.
Sperm have 23 chromosomes instead of the usual 46.

25. Did You Know?
Healthy sperm develop in the testes at a slightly lower temperature (as compared to normal body temperature). The position of the scrotum makes this possible.

26. Male Anatomy: in Summary
Sperm created in the testes and stored in the epididymis pass through the vas deferens and connect to a short ejaculatory duct that connects to the urethra. The urethra passes through the penis and opens to the outside. Secretions from the seminal vesicles provide nourishing fluid to sperm as they pass. The prostate gland also secretes a milky alkaline fluid. Sperm and secretions make up semen.

27. Anatomy of the Female

28. Anatomy of the Female: Ovaries
The ovaries, about the shape and size of almonds, produce female hormones (estrogen and progesterone) and eggs (ovum). All other reproductive organs act as accessories in transporting, nurturing and otherwise addressing the needs of the egg or developing fetus.

29. Female Reproductive Organ Histology
Access this website for an in-depth look at the female reproductive organ histology.

30. Anatomy of the Female: Fallopian Tubes
The fallopian tubes are approx. 10 cm long and begin as funnel-shaped passages next to the ovary.
When an egg is released by the ovary it is ‘caught’ and transported along the fallopian tube to the uterus.
The egg is transported along the fallopian tube by the action of cilia (hairy projections on the surfaces of cells) at the entrance of the fallopian tube, and smooth muscle contractions which line the tube.

31. Challenge question
What is this surgical procedure called? What is its purpose?

32. Fertilization
It takes the egg about 5 days to reach the uterus and it is on this journey down the fallopian tube that fertilization may occur if a sperm penetrates and fuses with the egg.
The egg, however, is only usually viable for hours after ovulation, so fertilization usually occurs in the top one-third of the fallopian tube.

35. Anatomy of the Female: The Uterus
The uterus is a hollow cavity about the size of a pear that exists to house a fertilized egg as it develops. The uterus has a narrow outlet to the vagina called the cervix.

36. Anatomy of the Female: The Vagina
The vagina is a muscular tube that extends from the cervix to the vulva.
The vagina receives the penis and semen during sexual intercourse and also provides a passageway for menstrual blood flow to leave the body.

37. Anatomy of the Female: The Genitals
The female external genitals are collectively known as the vulva.
The labia is a thin membrane of folded skin just outside the vaginal opening which covers and protects the genital area.
A clitoris, important in arousal, is a short shaft with a sensitive tip covered by a fold of skin.

38. Ovulation
The ovarian cycle usually lasts 28 days. During the first phase, the egg undergoes maturation.
At midpoint of the cycle, the egg is released from the ovary in a process known as ovulation.

39. Did You Know?....
Menopause is a natural event that normally occurs between the ages of 45 and 55 in women.
It is a transition period in which the ovaries stop producing eggs, producing less estrogen and progesterone. Menstruation becomes less frequent, eventually stopping altogether.

40. Fertilization
In the final stage of ovulation, the egg travels through the fallopian tube toward the uterus. If the egg is fertilized by a sperm (conception), "implantation" will take place in the uterine lining.

41. Challenge Question?
What is an ectopic pregnancy?

42. Fertilization cont.
Without fertilization, hormone levels decrease, causing the lining of the uterus to break down and shed - otherwise known as menstruation, or a woman's "period” marking the end of the menstrual cycle.

43. The Endocrine System and the Reproductive System

44. POP QUIZ! Label Structures A-M.
Be able to describe the role each plays as part of the reproductive system. A B G H E I F D M C J L K

45. “That’s All Folks!”
More to come…