The Male and Female Reproductive Systems

1. The Male and Female Reproductive Systems Exercise 42 & 47 A&P 233

2. Male Reproductive system Produces male games (sperm cells) in the seminiferous tubules in the testes Transports gametes to the female reproductive tract Secretes testosterone

3. Scrotum • The testes sit in the scrotum • Sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis • Contains paired testicles separated by a midline septum • Its external positioning keeps the testes 3C lower than core body temperature

4. Wall of the Scrotum • In the dermis, there is a thin layer of smooth muscle known as the dartos muscle. Contractions of this muscle causes wrinkling of the skin. • The cremaster muscle is a thicker layer of skeletal muscle that lowers and raises the testes based on temperature.

5. Inside the Scrotum • A fibrous (tough connective tissue) capsule covers each testis called the tunicaalbuginea.

6. Testicle • The tunica albuginea gives rise to septa (partitions) that divide the testis into lobules (about 250) • Each lobule contains 3 or 4 highly coiled seminiferous tubules • These converge to become rete testis which transport sperm to the epididymis

7. Cells of the testis • Interstitial cells: produce testosterone • Spermatogonia: reproduce by mitosis to produce primary spermatocytes. • Sustentacular (Sertoli) cells: form blood testis barrier (BTB), supplies nutrients to developing sperm, protect. (Also called nurse cells) • Primary spermatocytes divide by meiosis to form secondary spermatocytes which are located closer to the lumen of the tubule. • The process of sperm formation from spermatogonia to sperm cells is called spermatogenesis

8. Seminiferous Tubules

9. Seminiferous Tubules Histology

10. Spermatogenesis

11. Spermiogenesis: Spermatids to Sperm

12. Sperm • Sperm have three major regions • Head :contains DNA and has a helmet-like acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg • Midpiece: contains mitochondria spiraled around the tail filaments • Tail :a typical flagellum produced by a centriole

13. Epididymis • Epididymis: Storage and maturation area for sperm • Its head joins the efferent ductules and caps the superior aspect of the testis • The duct of the epididymis has stereocilia that: • Absorb testicular fluid • Pass nutrients to the sperm • Nonmotile sperm enter, pass through its tubes and become motile (propelled by peristalsis) • Upon ejaculation the epididymis contracts, expelling sperm into the ductus deferens

14. Epididymis histology

15. Spermatic Cord • Contains the structures running from the testicles to the pelvic cavity. • Passes through the inguinal canal • Contents: • Vas Deferens • Nerves • Blood Vessels

16. Accessory Glands: Seminal Vesicles • Lie on the posterior wall of the bladder and secrete 60% of the volume of semen • Seminal fluid: • Fructose and other carbohydrates: provides energy for the sperm. • As well as some protein, citrate and prostaglandins • Join the ductus deferens enlarges to form ampulla. • Each ductus deferens joins with the seminal vesicles which forms the ejaculatory ducts

17. Posterior Bladder

18. Posterior Bladder

19. Accessory Glands: Prostate Gland • Doughnut-shaped gland that encircles part of the urethra inferior to the bladder • Plays a role in the activation of sperm • Enters the prostatic urethra during ejaculation • Constitutes about 30% of semen. • Prostatic secretions function to: • Buffer the vaginal and seminal acidity, raising the pH to about 7.5 and activating the sperm (pH of the vagina is about 3.5 – 4.0)

20. Bulbourethral Glands (Cowper’s Glands) • Pea-sized glands inferior to the prostate • Add lubricant to the seminal fluid • Seminal fluid consists of secretions from the seminal vesicles, prostate gland and bulbourethral glands. • Semen consists of seminal fluid plus the sperm cells from the testes.

22. Penis Histology

23. Sperm Summary • Produced: Seminiferous tubules • Stored: Epididymis • Transported through epididymis by rhythmic peristaltic contractions as they mature • EpididymisVas DeferensEjaculatory duct (ampulla of vas deferens fuses with duct of seminal vesicle “ejaculatory duct”)  prostate prostatic urethra (then passes the bulbourethral gland) membranous urethrapenile urethra

24. Review questions • What is the difference between mitosis and meiosis? • What are the results of meiosis?

25. Spermatogenesis • Spermatogenic stem cells of the seminiferous tubules give rise to sperm in a series of events • Mitosis of spermatogonia, forming spermatocytes • Meiosis forms spermatids from spermatocytes • Spermiogenesis: spermatids form sperm

26. Vasectomy • Male sterilization • Cutting and tying of the two ductus deferens. • Prevents sperm from traveling from the testes to the spermatic cords • Sperm is reabsorbed by the body

27. The Female Reproductive System Exercise 47 A&P 233

28. Female Reproduction • Unlike males, who are able to produce sperm cells throughout their reproductive lives, females produce a finite number of egg cells. • During early fetal development germ cells migrate into the ovaries and differentiate into oogonia

29. Gross Anatomy • The ovaries are solid, ovoid structures, about 2 cm in length and 1 cm in width. • Like the testes, they develop from embryonic tissue along the posterior abdominal wall, near the kidneys. • Accessory organs include the uterine tubes, uterus, and vagina.

30. Ovaries • Each follicle consists of an immature egg called an oocyte • Cells around the oocyte are called: • Follicle cells (one cell layer thick) • Stimulated to mature by FSH from the pituitary gland • Granulosa cells (when more than one layer is present) • Thecal cells: Cells in the ovarian stroma • Thecal & granulosa cells work together to produce estrogen • A protective layer of glycoprotein forms around the egg called the zona pellucida

31. Ovary Histology

32. Primary Follicle 1° Oocyte(arrested in prophase I) Nucleus Zona pellucida Thecal cells Granulosa cells

33. Secondary Follicle Fluid-filled antrum

34. Graafian Follicle Fluid filled antrum Oocyte 2° Granulosa cells Stalk Corona radiata Zona pellucida

35. Ovarian Follicles

36. Follicle Development • Primordial follicle: one layer of squamous-like follicle cells surrounds the oocyte • Primary follicle: one or more layers of cuboidalgranulosa cells enclose the oocyte • Secondary follicle: has a fluid-filled space between granulosa cells that coalesces to form a central antrum • Graafian follicle: secondary follicle at its most mature stage that bulges from the surface of the ovary • Corpus luteum : ruptured follicle after ovulation

37. Corpus luteum • After ovulation, the remains of the follicle are transformed into a structure called the corpus luteum. • If a pregnancy occurs, it produces progesterone to maintain the wall of the uterus during the early period of development.

38. Corpus albicans • If fertilization does not occur, the corpus luteum will begin to break down about 2 weeks after ovulation. • Degeneration occurs when fibroblasts enter the corpus luteum and a clump of scar tissue forms called the corpus albicans.

39. Uterine Tubes (Fallopian Tubes) • Receive the ovulated oocyte and provide a site for fertilization • The ampulla ends in the funnel-shaped, ciliated infundibulum containing fingerlike projections called fimbriae • Expand distally around the ovary forming the ampulla • Empty into the superolateral region of the uterus via the isthmus

40. Uterine Tubes (Fallopian Tubes) • Fimbriae sweep oocyte into tube, cilia & peristalsis move it along, sperm reaches oocyte in ampulla, fertilization occurs within 24 hours after ovulation & zygote reaches uterus about 7 days after ovulation

41. Fallopian Tube Histology Cilia sweep egg/zygote toward the uterus

42. Uterus • Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder • Body: Major portion of the uterus • Fundus: Rounded region superior to the entrance of the uterine tubes • Isthmus: Narrowed region between the body and cervix

43. Uterus

44. Uterine Histology • Endometrium • Simple columnar epithelium • Stroma of connective tissue and endometrial glands • Stratum functionalis: Shed during menstruation • Stratum basalis: Replaces stratum functionalis each month • Myometrium • 3 layers of smooth muscle • Perimetrium • Visceral peritoneum

45. Uterine Histology

46. Endometrium Simple columnar epithelium Endometrial glands

47. Endometrium • Proliferative phase: glands and blood vessels scattered throughout the functional zone with little or no branching. • New glands form and endometrium thickens. • Secretory phase: glands are enlarged and have branches. Preparing the endometrium for implantation • If no implantation then endometrium breaks down and menstruation begins.

48. Cervix • Narrow lower neck of the uterus which projects into the vagina inferiorly • Cervical canal – cavity of the cervix that communicates with: • The vagina via the external os • The uterine body via the internal os • Cervical glands secrete mucus that covers the external os and blocks sperm entry except during midcycle

49. Endocervical canal Fornix

50. Ovarian and Uterine Cycles