CHAPTER 19: REPRODUCTIVE SYSTEMS 19.1 INTRODUCTION Produce and nurture sex cells.

1. CHAPTER 19: REPRODUCTIVE SYSTEMS 19.1 INTRODUCTION • Produce and nurture sex cells. • Transport them to sites of fertilization. • Male sex cells: sperm • Female sex cells: eggs/oocytes • Sex cells: haploid 23 chromosomes • Secrete hormones that develop and maintain sex characteristics and regulation of reproductive physiology.

2. 19.2 ORGANS OF THE MALE REPRODUCTIVE SYSTEM • Gonad/testes: primary sex organs; where sperm cells and male sex hormones form. • Accessory sex organs: internal and external reproductive organs.

4. TESTES • Ovoid structures about 5 centimeters in length and 3 centimeters in diameter. • Both testes are within the cavity of the saclike scrotum. STRUCTURE OF THE TESTES • Tough, white, fibrous capsule encloses each testis. • Posterior border, the connective tissue thickens and extends into the testis, forming thin septa that divide the testis into 250 lobules.

5. Each lobule contains one to four highly coiled, convoluted seminiferoustubules. (70 cm. long uncoiled) • Unite posteriorly and unite to form a network of channels.

6. Channels give rise to several ducts that join a tube called the epididymis. • Epididymis coils on the outer surface of the testis and continues to become the vas deferens. Pg. 492

7. Spermatogeniccells: specialized stratified epithelium that give rise to sperm cells, lines the seminiferous tubules. • Interstitialcells (cells of Leydig): lie in the spaces between the seminiferous tubules; produce and secrete male sex hormones. • Epithelial cells could give rise to testicular cancer. • Symptoms: first painless testis enlargement or a scrotal mass that attaches to a testis.

8. FORMATIONOFSPERMCELLS • Sertoli cells (supporting cells) and spermatogenic cells: cells of the epithelium of the seminiferous tubules. • Supporting cells provide a scaffolding for the spermatogenic cells, and also nourish and regulate them.

9. Males produce sperm cells continually throughout their reproductive lives. • Sperm cells collect in the lumen of each seminiferous tubule. • Then pass to the epididymis, where they accumulate and mature.

10. A mature sperm cell is a tiny, tadpole-shaped structure about 0.06mm long. • Flattened head, cylindrical midpiece (body), and an elongated tail. • Head: nucleus and, compacted chromatin, protrusion at its anterior end, called the acrosome, contains enzymes that help the sperm cell penetrate an egg cell during fertilization.

11. Midpiece of a sperm cell has a central, filamentous core and many mitochondria in a spiral. • Tail (flagellum) • Mitochondria provide ATP for the tail’s lashing movement.

12. SPERMATOGENESIS • Formation of sperm cells. • In a male embryo, spermatogenic cells are undifferentiated, called spermatogonia. • Contains 46 chromosomes in its nucleus. • During embryonic development, hormones stimulate spermatogonia to undergo mitosis and some of them enlarge to become primary spermatocytes. • Supporting cells help sustain the developing sperm cells.

13. PUBERTY • Primary spermatocytes then reproduce by a special type of cell division call meiosis. • Different combination in each sperm. • Haploid • Each primary spermatocyte divides to form two secondary spermatocytes. • Each of these cells divide into two spermatids. • Spermatids mature into sperm cells.

15. Video / quiz • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__spermatogenesis__quiz_1_.html

16. MALEINTERNALACCESSORYORGANS • Nurture and transport sperm cells. Structures: • Epididymides • Vasadeferentia • Ejaculatory ducts • Urethra • Seminal vesicles • Prostate gland • Bulbourethral glands

17. EPIDIDYMIS (epi - did - i-mis) • Tightly coiled, threadlike tube about 6 meters long. • Connected to ducts within the testis. • Emerges from the top of the testis. • Descends along the posterior surface of the testis, and then courses upward to become the vas deferens.

18. Immature sperm cells reaching the epididymis are nonmotile. • Rhythmic peristaltic contractions help move these cells through the epididymis, the cells mature. • Have potential to move independently but do not “swim” until ejaculation.

19. VASDEFERENS (vas def erenz) • Muscular tube about 45 cm. • Passes upward along the medial side of a testis and through a passage in the lower abdominal wall. • Enters the pelvic cavity • Ends behind the urinary bladder. • Unites with the duct of the seminal vesicle to form an ejaculatoryduct. • Passes through the prostate gland and empties into the urethra.

20. SEMINALVESICLE • Convoluted, saclike structure about 5 cm long that is attached to the vas deferens near the base of the urinary bladder. • Glandular tissue lines the inner wall of the seminal vesicle and secretes a slightly alkaline fluid.

21. Fluid helps regulate the pH of the tubular contents as sperm cells travel to the outside. • Seminal vesicle secretions also contain fructose, provides energy to sperm cells. • Prostaglandins, stimulate muscular contractions within the female reproductive organs, aiding the movement of sperm cells toward the egg cell.

24. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/simple_multiple_choice.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/simple_multiple_choice.html