Lecture 20 Reproductive Systems Chapters 19

1. Lecture 20 Reproductive Systems Chapters 19

2. Gamete production – male vs. female • Diploid to haploid • What can go wrong? • Where and when • How does this differ in males and females? • Type of division • How does sexual reproduction give rise to variation? • Hormonal control • Reproductive systems • gonads, ducts, glands • Gynecology • Urology

4. Meiosis and Gamete Production • Differs in Males and Females • Males: 4 sperm/primary spermatocyte • Females: secondary oocyte released at ovulation – nucleus at end of meiosis I • IF FERTILIZATION OCCURS: meiosis completed and haploid nucleus produced

5. Male Reproductive System • Sperm production: Testes • Maturation: Epididymides • Location in scrotum important due to cooler temperature • Hormone Production • Interstitial cells – (between seminiferous tubules) • Testosterone (an androgen) • Inhibin – regulates sperm count

7. Functions of Testes: • Sperm production • Seminiferous tubules • Release of endocrine hormones • Interstitial cells  testosterone • Sustenacular (Seritoli cells)  inhibin

8. Testes • Paired oval glands measuring 2 in. by 1in. • Surrounded by dense white capsule – tunica vaginalis • septa form 200 - 300 compartments called lobules • Each is filled with 2 or 3 seminiferous tubules where sperm are formed

10. Spermatogenesis • Spermatogonium (stem cells) give rise to 2 daughter cells by mitosis • One daughter cell kept in reserve -- other becomes primary spermatocyte • Primary spermatocyte goes through meiosis I • DNA replication • tetrad formation • crossing over

12. Sperm Morphology • Adapted for reaching & penetrating a secondary oocyte • Head contains DNA & acrosome (hyaluronidase and proteinase enzymes) • Midpiece contains mitochondria to form ATP • Tail is flagellum used for locomotion

13. Epididymis • Comma-shaped organ, 1.5in long along posterior border of each testis • Head, body and tail region • Multiple efferent ducts become a single ductus epididymis in the head region • 20 foot tube if uncoiled • Tail region continues as ductus deferens

14. Ductus (Vas) Deferens • Pathway of 18 inch muscular tube • ascends along posterior border of epididymis • passes up through spermatic cord and inguinal ligament • reaches posterior surface of urinary bladder • empties into prostatic urethra with seminal vesicle • Lined with pseudostratified columnar epithelium & covered with heavy coating of muscle • convey sperm along through peristaltic contractions • stored sperm remain viable for several months

15. Vasectomy • Male sterilization • Vas deferens cut & tied off • Sperm production continues • Sperm degenerate • 100% effective • 40% reversible

16. Inguinal Canal & Inguinal Hernias • Inguinal canal is 2 inch long tunnel passing through the3 muscles of the anterior abdominal wall -- weakens wall • originates at deep inguinal ring and ends at superficial ring • Indirect hernia -- loop of intestine protruding through deep ring • Direct hernia -- loop of intestine pushes through posterior wall of inguinal canal • More common in males

17. Accessory Sex Glands

18. Semen • Sperm + seminal fluid • Seminal fluid - Secretions from seminal vesicles, prostate and bulbourethral glands • buffered to 7.4 • includes energy source • Prostaglandins (uterine contractions) • Provides for survival of sperm for up to 48 hours

19. Urethra • 8 inch long passageway for urine & semen • Prostatic urethra (1 inch long) • Membranous urethra (passes through UG diaphragm ) • Penile (spongy) urethra (through corpus spongiosum)

20. Penis • Passageway for semen & urine • Body composed of three erectile tissue masses filled with blood sinuses • Composed of bulb, body & glans penis

21. Aging Male Reproductive System • Decline in reproductive function is more subtle (capacity may remain into 90’s) • Decline in testosterone at 55 • reduced muscle synthesis • fewer viable sperm • reduced sexual desire • Enlargement of prostate (benign hyperplasia) • 1/3 of males over 60 • frequent urination, decreased force of stream, bed-wetting & sensation of incomplete emptying

22. Prostate Cancer • Leading male cancer death • treatment is surgery, radiation, hormonal and chemotherapy • Blood test for prostate-specific antigen (PSA) • enzyme of epithelial cells • amount increases with enlargement (indication of infection, benign enlargement or cancer) • Over 40 yearly rectal exam of prostate gland • acute or chronic prostatitis is an infection of prostate causing swelling, tenderness & blockage of urine flow • treat with antibiotics

24. Ovaries: secured to uterus by ovarian ligament, pelvic cavity wall by round ligament • Uterine or Fallopian Tubes: Narrow, 4 inch tube from ovary to uterus • fimbriae are moving finger-like processes • Lined with ciliated columnar epithelium

25. Review of Oogenesis

27. What occurs here? • Description • 3 inches long by 2 in. wide and 1 in. thick • Regions: • fundus,body, isthmus & cervix • interiorly contains uterine cavity accessed by cervical canal • (internal & external os)

28. Position of Uterus

29. Histology of the Uterus • Endometrium • simple columnar epithelium • stroma of connective tissue and endometrial glands • Myometrium • 3 layers of smooth muscle • Perimetrium • visceral peritoneum (serous membrane)

30. Hysterectomy • Surgical removal of the uterus • Indications for surgery • endometriosis, ovarian cysts, excessive bleeding, cancer of cervix, uterus or ovaries • Complete hysterectomy removes cervix • Radical hysterectomy removes uterus, tubes, ovaries, part of vagina, pelvic lymph nodes and supporting ligaments

31. Hormonal Control of Ovarian and Menstrual Cycles From Anterior Pituitary • FSH stimulates development of follicle in ovary • Luteinizing hormone – triggers ovulation From Ovaries (follicle cells/corpus luteum) • Estrogen – preparation of uterine lining for implantation • Progesterone – maintenance of endometrium

32. Vulva • Mons pubis -- fatty pad over the pubic symphysis • Labia majora & minora -- folds of skin encircling vestibule where find urethral and vaginal openings • Clitoris -- small mass of erectile tissue • Bulb of vestibule -- masses of erectile tissue just deep to the labia on either side of the vaginal orifice

33. Mammary Glands • Modified sweat glands that produce milk (lactation) • amount of adipose determines size of breast • milk-secreting glands open by lactiferous ducts at the nipple • areola is pigmented area around nipple • suspensory ligaments suspend breast from deep fascia of pectoral muscles (aging & Cooper’s droop)

34. Female Reproductive Cycle • Controlled by monthly hormone cycle of anterior pituitary, hypothalamus & ovary • Monthly cycle of changes in ovary and uterus • Ovarian cycle • changes in ovary during & after maturation of oocyte • Uterine cycle • preparation of uterus to receive fertilized ovum • if implantation does not occur, the stratum functionalis is shed during menstruation

35. Hormonal Regulation of Reproductive Cycle • GnRH secreted by the hypothalamus controls the female reproductive cycle • stimulates anterior pituitary to secrete FSH & LH • FSH initiates growth of follicles that secrete estrogen • estrogen maintains reproductive organs • LH stimulates ovulation & promotes formation of the corpus luteum which secretes estrogens, progesterone, relaxin & inhibin • progesterone prepares uterus for implantation and the mammary glands for milk secretion • relaxin facilitates implantation in the relaxed uterus • inhibin inhibits the secretion of FSH

39. In Vitro Fertilization (IVF) • Laboratory Procedures • Obtain immature eggs from ovary • Mature eggs in laboratory • In Vitro fertilization – sperm introduced • Embryo develops – 3-4 days • Embryo implanted in uterus

41. The End.