Biology 30 Human Reproduction & Development

1. Biology 30Human Reproduction & Development Anatomy of the Male and Female Reproductive Systems Gamete Formation Hormonal Control of Reproduction Conception, Pregnancy, Development, Birth

2. Biology 30 Male Reproductive Anatomy

3. You solve the problem. • “Recently I have experienced my right testicle slipping upwards into my body and ‘disappearing’. It can be felt through the skin, and then can be slid back down. The only pain is a dull ache that ensues. It seems to require some pressure on the scrotum to occur, such as my wife being ‘frisky’. Is there a term and/or a treatment for this? Is it serious?” December 7, 1999

4. Anatomy of the Male Reproductive System • External genitalia • Penis and Scrotum • Internal Reproductive Organs • Pair of gonads • Produce gametes (sperm cells) • Produce hormones • Accessory glands • Secret products essential to sperm movement • Set of ducts • Carry sperm and glandular secretions.

6. Penis Scrotum

7. Anatomy of the Male Reproductive System • Penis • Composed of 3 cylinders of spongy tissue. • During sexual arousal, tissue fills with blood from the arteries • The increasing pressure seals off the veins that drain the penis • Result = penis engorges with blood = erection • The tip (Glans) is covered by a fold of skin called the foreskin, which may be removed by circumcision • A tradition with religious roots. • No verifiable health or hygienic advantage.

8. Foreskin

9. Anatomy of the Male Reproductive System • Scrotum • Sac which contains testes • Regulates temperature of testes by contraction of cremaster muscle. • Cold = contracts • Brings testes close to body to warm up. • Warm = relaxes • Goal = keep testes 3o below normal body temperature.

10. Cremaster Muscle Testis

12. Anatomy of the Male Reproductive System • Testes • Stored in scrotum • Before birth, testes develop in the abdomen and then migrate down a canal into scrotum around the time of birth. • Sperm producing organ • Made in tightly coiled tubes called seminiferous tubules inside testes • Sperm produced is not fully mature when it leaves testis (not motile yet) • Source of male hormone testosterone • Made by interstitial cells scattered between the seminiferous tubules • Deposits sperm into epididymis

13. Seminiferous Tubules

14. Epididymis

15. Epididymis

16. Epididymis

17. Anatomy of the Male Reproductive System • Epididymis • Coiled tubes • About 6 meters long!! • Posterior to the testis • Stores sperm • Site of further sperm maturation • Gains motility • Contracts during ejaculation, expelling sperm into vas deferens • Sperm can be store here for months • If not ejaculated, will eventually be phagocytized

18. Vas Deferens

19. Vas Deferens

20. Anatomy of the Male Reproductive System • Vas Deferens • Muscular tubes that carry sperm from epididymis to ejaculatory duct (and eventually the urethra) • peristalsis • Urethra drains both the excretory system and the reproductive system • Not the case in females

21. Ejaculatory Duct

22. Anatomy of the Male Reproductive System • Ejaculatory Duct • Connects seminal vesicle to urethra • Passes through prostate gland

23. Seminal Vesicle

24. Seminal Vesicle

25. Anatomy of the Male Reproductive System • Seminal Vesicle • Lies below and behind bladder • Secretes thick, clear fluid into ejaculatory duct • 60% volume of semen (the fluid that is ejaculated) • Alkaline – to neutralize acidic pH of vagina • Fructose – used for energy by sperm • Prostaglandins – chemical messengers which, once in female, stimulate uterine peristalsis to help move semen up the uterus • Proteins – cause semen to coagulate after it is deposited in the female, making it easier for the uterine contractions to move the semen

26. Prostate Gland

27. Prostate

28. Anatomy of the Male Reproductive System • Prostate Gland • Doughnut shaped gland which surrounds urethra • Secretes thin milky fluid into urethra • 20% of seminal volume • Liquefy the semen – prevents sperm from clumping together • Alkaline – continues to neutralize acid from residual urine in urethra and natural acidity of vagina • Prostate Source of most common medical problems of men over 40. Benign enlargement in over ½ of all men in the age group.

29. Anatomy of the Male Reproductive System • Cowper’s Gland (Bulbourethral Gland) • Pair of small glands along urethra, below the prostate • Secrete viscous fluid before emission of sperm & semen • Thought to lubricate penis and vagina • Released before ejaculation • Fluid does contain some sperm • One factor in the high failure rate of the “withdrawal method” of birth control.

30. Cowper's Gland

31. Cowper's Gland

32. Anatomy of the Male Reproductive System • Vasectomy • Incision through scrotum • Cut and tie off vas deferens • Sperm is still produced but can’t get out • Phagocytized • Increased risk of prostate cancer

36. I'm Not Really Trying To Gross You Out! But Get Ready...

37. Tim

39. Anatomy of the Male Reproductive System • Passageway from testes to outside • Multiple seminiferous tubules • site of spermatogenesis • Single tubed epididymis • Vas deferens • Seminal vesicle • Ejaculatory duct • Urethra

40. Anatomy of the Male Reproductive System • For Your Information • Volume of ejaculation = 2.75 ml • pH = 7.2 – 7.6 • 50 – 150 million sperm per ml. • Only a few sperm reach the egg • Average sperm count has decreased from 113 million/ml to 66 million/ml in past 40 years. • Infertility = <20 million/ml • Factors leading to infertility are environmental toxins, estrogens in meat, radiation,pesticides, marijuana, alcohol

41. Solution to the medical problem. Remember that before birth, the testes develop in the abdomen, and then migrate down into the scrotum at birth. The pathway they follow through the layers of the abdominal wall on each side is called the inguinal canal. Usually, when the testes have completed their descent they remain permanently within the scrotum from that time on. The slightly lower temperature in the scrotum is more favorable to sperm production after puberty. Slender bundles of muscle fibers derived from the middle layer the abdominal muscle are

42. Solution to the medical problem. drawn into loops around the descending testis and form what is know as the cremaster muscle. During sexual arousal, the smooth muscle of the scrotum contracts too. As a result, the testes are transiently held in a more protected position during sexual intercourse. It is possible that your right testis has remained more mobile that usual, and is drawn back partially in the to inguinal cal by contraction of the cremaster muscle during sexual activity. This is referred to as

43. Solution to the medical problem. a “retractile testis”. If you at all concerned about this possibility, it will be worthwhile visiting your doctor to discuss the situation and whether or not any treatment is required.

44. Pubic Bone Seminal Vesicles Rectum Prostate Gland Cowper’s Gland Anus Vas Deferens (sperm duct) Epididymis Testes Urethra Penis Scrotum Head of Penis (Glans) Foreskin Bladder Labelling Diagram

45. Biology 30 Female Reproductive Anatomy

46. Anatomy of the Female Reproductive System • Consists of: • External genitalia • Two sets of labia that surround the clitoris and vaginal opening • Internal Reproductive Organs • A pair of gonads (ovaries) • A system of ducts and chambers to • Conduct the gametes • House the embryo and fetus

47. External Genitalia

48. Internal Organs

49. Internal Organs

50. Anatomy of the Female Reproductive System • Ovaries • Lie in abdomen, below most of the digestive system • Enclosed in a tough protective capsule • Produces eggs (follicles) • Produces female sex hormones • Estrogen • Progesterone