Chapter 16: The Reproductive System

1. Chapter 16: The Reproductive System Students will be able to understand the male reproductive and female reproductive systems

2. The Reproductive System • General Information • 1. Divided into male and female • 2. Both systems contain gonads or primary sex organs • Produce gametes

3. I. Male Reproductive Anatomy • A. Primary reproductive organs are the testes (male gonads) • Have both exocrine (sperm-production) and endocrine (testosterone-production) function • B. Secondary reproductive organs are those used for storage and movement of sperm • 1. Ducts and Tubules • 2. Also called accessory reproductive structures

4. Testes

5. Mammal Testes

6. I. Male Reproductive Anatomy • C. Testes • 1. Are approximately 4 cm long • 2. Are approximately 2.5 cm wide • 3. The tunica albuginea, (a fibrous connective tissue), surrounds the testes • 4. The septa are extensions of the tunica albuginea that divide the testes into lobules • a. Lobules contain 1-4 tightly coiled seminiferous tubules • Seminiferous tubules form the sperm

8. Tunica Albuginea – Cross Section

9. Seminiferous Tubules

10. Seminiferous tubules – Cross Section

11. I. Male Reproductive Anatomy • C. Testes • Interstitial cells, lie in the soft connective tissue surrounding the seminiferous tubules, which produce androgens (i.e. testosterone) • 5. The rete testis are tubules the sperm move into after production • 6. Sperm move through the rete testis into the first duct or storage unit • a. Lies along the external surface of the testes

12. Testicular Cross Section with Spermatocytes (spermatogonia)

16. I. Male Reproductive Anatomy • D. Duct System • 1. Consists of the: • a. Epididymis • b. Ductus deferens • c. Ejaculatory duct • d. Urethra

17. Epididymis

19. I. Male Reproductive Anatomy • D. Duct system • a. epididymis • Lies along the exterior surface of the testes • Comma-shaped • Highly coiled • Can be 6 m long (approx. 20 ft) • Lies superior to the testes, runs down the posterolateral side • Temporary storage system • Takes 20 days to pass through

20. I. Male Reproductive Anatomy • D. Duct system • b. Ductus Deferens • Also called the vas deferens • Runs upward from the epididymis • Moves through the inguinal canal into the pelvic cavity • Arches over the urinary bladder to the prostrate gland • The tube is enclosed by the spermatic cord • Also has blood vessels and nerve bundles • Propels live sperm from storage to the ejaculatory duct • Vasectomy occurs along this duct (cut and cauterize)

21. I. Male Reproductive Anatomy • D. Duct System • c. Ejaculatory Duct • Passes through the prostate gland • Merges with the urethra • Smooth walls create peristaltic waves during ejaculation • Squeezes sperm forward

23. I. Male Reproductive Anatomy • D. Duct System • d. Urethra • Extends from the base of the bladder to the tip of the penis • 3 regions • Prostatic urethra: surrounded by the prostate gland • Membranous urethra: between the prostrate and the base of the penis • Spongy urethra: length of the penis

27. I. Male Reproductive Anatomy • E. Accessory glands and semen • 1. Seminal Vesicle • a. Located at the base of the bladder • b. Produces 60% of the fluid (by volume) of the semen • c. The secretion is rich in sugar (fructose), vitamin C, prostoglandins, etc.. • Used to nourish sperm • Provide energy conversion capabilities • May play a role in ovulation and corpus luteum function • d. Joins the urethra at the connection with the vas deferens (the combination is called the ejaculatory duct)

28. Seminal Vesicle

29. Seminal Vesicle

31. I. Male Reproductive Anatomy • E. Accessory Glands and Semen • 2. Prostate Gland • a. Single gland • b. Encircles the urethra • c. Secretes a milky white fluid that activates the sperm • d. Alkaline, which protects the sperm from the acid environment of the vaginal area • e. Prostrate glandular secretions is (approximately) 40% of the fluid by volume

32. Prostate Gland

33. I. Male Reproductive Anatomy • E. Accessory Glands and Semen • 3. Bulbourethral glands • a. Once called Cowper’s glands • b. Are pea-sized • c. Produce a thick clear mucus • d. It is the first fluid down the urethra during stimulation • e. Used to lubricate • f. There is some debate over “whether there is sperm leaked into this fluid during stimulation”

34. Cowper’s Gland (Bulbourethral glands)

35. I. Male Reproductive Anatomy • E. Accessory Glands and Semen • 4. Semen • a. Milky white mixture • b. It is sticky • c. Has sperm and other glandular secretions • 40 to 2.5 million sperm • d. The liquid is a transport medium • e. Has nutrients and chemicals (used to protect sperm) • f. The pH is between 7.2 – 7.8 • g. Contains seminalplasmin, relaxin, and several enzymes • Sp helps to coagulate the semen, after 15 minutes becomes liquid again

36. I. Male Reproductive Anatomy • F. External Genitalia • 1. 2 parts • a. The scrotum • The testes hang outside of the male body • Sperm are not produced at normal body temperature • The temperature is about 5 degrees cooler • If the outside temperature cools the testes are pulled toward the body

37. I. Male Reproductive Anatomy • F. External Genetalia • 1. 2 parts (cont) • b. The penis • Hangs outside of the body • Is designed to deliver sperm to the female body • Has a shaft • An enlarged tip (glans penis) • A loose skin, that folds to cover the tip, foreskin or prepuce • Circumcision is the removal of the foreskin • Internally the spongy urethra is surrounded by 3 areas of erectile tissue that fills with blood during stimulation

38. I. Male Reproductive Anatomy • G. Male reproductive functions • 1. Spermatogenesis • a. The production of sperm via meiosis • b. Creates 4 sperm with each meiotic event • Each sperm is haploid (half the chromosomes) • Allows for genetic variation • c. Spermatogonia are stem cells in the seminiferous tubules which produce more stem cells until puberty and then divide meioticly to form other cells

39. I. Male Reproductive Anatomy • G. Male reproduction functions • 1. Spermatogenesis (cont) • d. The change over occurs due to the hormone, follicle stimulating hormone (FSH) • During cell division a stem cell is produced (type A), and a primary spermatocyte (type B) • Spermatocytes will then undergo meiosis and produce sperm

40. I. Male Reproductive Anatomy • H. Testosterone Production • 1. Produced by the interstitial cells • 2. Most important hormone produced by the testes • 3. Are activated by the hormone luteinizing hormone (LH) • a. Also called interstitial cell – stimulating hormone (ICSH) • b. Released by the anterior pituitary gland • 4. Activate other secondary sex characteristics • a. Deeper voice, increased hair growth, enlargement of the skeletal muscles, etc.

41. II. Female Reproductive system • A. General Information • More complex than the male reproductive system • Must produce gametes • Must nurture and protect developing fetus

42. II. Female Reproductive system • B. Ovaries • 1. Primary reproductive organ • 2. Produce both endocrine products (estrogens and progesterone) and exocrine products (eggs/ova) • 3. The size of almonds • 4. Has many sac-like structures called ovarian follicles

43. Ovaries

44. Ovaries

45. Ovarian Follicles

46. Ovarian Follicles

47. II. Female Reproductive system • B. Ovaries • 5. Ovarian follicles carry an immature egg called an oocyte • a. Surrounded by follicle cells • b. Ova mature over time, the follicle enlarges, becomes fluid filled (central region is called the atrum) • The follicle is now called a Graafian or vesicular follicle, containing a mature ova called a secondary oocyte • Will be ejected during ovulation • The follicle is now called a corpus luteum

48. Oocyte

49. Oocyte

50. Oocyte development