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REPRODUCTIVE SYTEM

REPRODUCTIVE SYTEM. MALE REPRODUCTIVE ORGANS. ANATOMY OF THE MALE REPRODUCTIVE SYSTEM. The scrotum is a sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis and houses the testes

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REPRODUCTIVE SYTEM

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  1. REPRODUCTIVE SYTEM

  2. MALE REPRODUCTIVE ORGANS

  3. ANATOMY OF THE MALE REPRODUCTIVE SYSTEM • The scrotum is a sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis and houses the testes • Provides an environment three degrees below the core body temperature • Responds to temperature changes: help maintain a fairly constant intrascrotal temperature and reflects the activity of two sets of scrotal muscles • When it is cold, the testes are pulled closer to the warmth of the body wall, and the scrotum becomes shorter and heavily wrinkled to reduce heat loss • When it is warm, the scrotal skin is flaccid and loose to increase the surface area for cooling, and the testes hang lower

  4. TESTIS STRUCTURE

  5. ANATOMY OF THE MALE REPRODUCTIVE SYSTEM • The testes are the primary reproductive organ of the male, producing both sperm and testosterone • The testes are divided into lobules with seminiferous tubules inside, where sperm are produced • Each lobule converge to form a tubule that conveys sperm to the epididymis which hugs the external testis surface • Interstitial cells are found in the connective tissue surrounding the seminiferous tubules and produce testosterone

  6. INTERNAL STRUCTURE OF TESTIS

  7. ANATOMY OF THE MALE REPRODUCTIVE SYSTEM • Spermatic cord: connective tissue sheath enclosing: • Testicular arteries • Testicular veins • Lymph vessels • Nerves • Vas (ductus) deferens

  8. INTERNAL STRUCTURE OF TESTIS

  9. TESTIS STRUCTURE

  10. MALE REPRODUCTIVE ORGANS

  11. HOMEOSTATIC IMBALANCE • Although testicular cancer is relatively rare, it is the most common cancer in young men (15-35) • A history of mumps or orchitis (inflammation of the testis) increases the risk, but the most important risk factor for this cancer is cryptorchidism (nondescent of the testes)

  12. ANATOMY OF THE MALE REPRODUCTIVE SYSTEM • The penis is the copulatory organ, designed to deliver sperm into the female reproductive tract: • The penis is made of an attached root, a free shaft or body that ends in the glans • The prepuce, or foreskin, covers the penis and may be slipped back to form a cuff around the glans • Removed in a procedure called circumcision • Internally the penis contains the corpus spongiosum (surrounds the urethra) and the corpora cavernosum (paired dorsally), two erectile tissues: • Spongy network of connective tissue and smooth muscle riddled with vascular spaces • During sexual excitement, the vascular spaces fill with blood, causing the penis to enlarge and become rigid (erection) • Enables the penis to serve as a penetrating organ

  13. STRUCTURE OF PENIS

  14. Male Duct SystemEpididymis • Epididymis consists of a highly coiled tube that provides a place for immature sperm to mature and to be expelled during ejaculation • Gain increased motility and fertilizing power • When a male is sexually stimulated and ejaculates, the smooth muscle in the epididymis walls contracts, expelling sperm into the next segment of the duct system, the ductus (vas) deferens • Sperm can be stored in the epididymis for several months, but if held longer, they are eventually phagocytized by epithelial cells of the epididymis

  15. Male Duct SystemDuctus Deferens and Ejaculatory Duct • The ductus deferens, or vas deferens, carries sperm from storage sites in the epididymis, through the inguinal canal, over the urinary bladder, and into the ejaculatory duct • Each ejaculatory duct enters the prostate gland where it empties into the urethra • Smooth musclesin its walls create strong peristaltic waves that rapidly squeeze the sperm forward

  16. Male Duct SystemDuctus Deferens and Ejaculatory Duct • Vasectomy: • Minor operation in which a small incision is made into the scrotum and then cuts through and ligates (ties off/ cut) the ductus (vas) deferens • Sperm are still produced for the next several years, but they can no longer reach the body exterior • They deteriorate and are phagocytized

  17. Vasectomy

  18. Vasectomy

  19. Vasectomy

  20. Vasectomy

  21. Male Duct SystemUrethra • The urethra is the terminal portion of the male duct system and carries both urine and sperm (not at the same time) to the exterior environment

  22. MALE REPRODUCTIVE ORGANS

  23. THE MALE REPRODUCTIVE SYSTEMAccessory Glands • The pairedseminal vesicles: on the posterior urinary bladder wall: accounts for 60%of the volume of semen • Fluid produced contains: • An alkaline secretion: • Neutralizes the acid environment of the male’s urethra and the female’s vagina, thereby protecting the delicate sperm and enhancing their motility • Coagulating enzyme (vesiculase) • Coagulates the semen after it is ejaculated • Liquified by enzyme fibrinolysin • Provides nearly all the nutrients • Fructose, ascorbic acid • Prostaglandins: decreases the viscosity of mucus guarding the entry (cervix) of the uterus and stimulates reverse peristalsis in the uterus, facilitating sperm movement through the female reproductive tract

  24. MALE REPRODUCTIVE ORGANS

  25. THE MALE REPRODUCTIVE SYSTEMAccessory Glands • The singleprostate gland: milky fluid about 30% of semen • Fluid produced: • A slightly acidic secretion • Citrate: compound of citric acid and a base (nutrient source) • Several enzymes: • Fibrinolysin: liquifies the coagulated mass due to the coagulating enzyme vesiculase • Enables the sperm to swim out of the mass and begin their journey through the female duct system • Hyaluronidase: breaks down covering of ovum • Acid phosphate: demineralization or resorptioin of bone • Prostate-specific antigen (PSA): increases sperm motility

  26. MALE REPRODUCTIVE ORGANS

  27. THE MALE REPRODUCTIVE SYSTEMAccessory Glands • The paired bulbourethral glands,or Cowper’s glands: • Produce a thick, clear mucus prior to ejaculation that neutralizes any acidic urine in the urethra and female vagina

  28. MALE REPRODUCTIVE ORGANS

  29. SEMEN • Semen is a milky white, somewhat sticky mixture of sperm and accessory gland secretions that provide nutrients, neutralizing agents, and transport medium for sperm: • Additional components: • Hormone relaxin: enhance sperm motility • pH: 7.2-7.6 • Helps neutralize the acid environment of the male urethra and the female’s vagina • Very sluggish in acidic conditions (below pH 6) • Antibiotic: seminalplasmin • Destroys certain bacteria • 2-5 ml per ejaculation (50-130 million sperm per millimeter)

  30. MALE REPRODUCTIVE ORGANS

  31. PHYSIOLOGY OF THE MALE REPRODUCTIVE SYSTEM • Male Sexual Response: • Erection, enlargement, and stiffening of the penis results from the engorgement of the erectile tissues with blood triggered during sexual excitement • Ejaculation is the propulsion of semen from the male duct system triggered by the sympathetic nervous system

  32. Erection • Enlargement and stiffening of the penis • Results from the engorgement of the erectile bodies with blood • Not sexually aroused: • Arterioles supplying the erectile tissue are constricted and the penis is flaccid • During sexual excitement: • Parasympathetic reflex is triggered that promotes release of nitric oxide locally • Nitric oxide (NO)relaxes vascular smooth muscle, causing these arterioles to dilate • Allows the erectile bodies to fill with blood • Expansion of the corporacavernosa of the penis compresses their drainageveins, retarding blood outflow and maintaining engorgement • Corpus spongiosum expands but not nearly as much as the cavernosa • Its main job is to keep the urethra open during ejaculation • Stimulates the bulbourethral (Cowper’s) gland secretion which causes lubrication of the glans penis

  33. Ejaculation • Propulsion of semen from the male duct system: • While erection is under parasympathetic control, ejaculation is under sympathetic control • When impulses provoking erection reach a certain critical level, a spinal reflex is initiated, and a massive discharge of nerve impulses occurs over the sympathetic nerves serving the genital organs (L1 and L2) causes: • Climax/orgasm: • The reproductive ducts and accessory glands contract, emptying their contents into the urethra • The urinary bladder sphincter muscle constricts, preventing expulsion of urine or reflux of semen into the urinary bladder • The bulbospongiosus muscles of the penis undergo a rapid series of contraction, propelling semen at a speed of up to 500 cm/s (200 inches/s) from the urethra

  34. STRUCTURE OF PENIS

  35. Spermatogenesis • A series of events in the seminiferous tubules that produce male gametes (sperm or spermatozoa) • Every day, a healthy adult male produces about 400 million sperm

  36. HUMAN LIFE CYCLE • Diploid (Somatic cells) chromosomal number (2n): 46 • 23 homologous pairs • One member of each pair from Mom • One member of each from Dad • Therefore: • 23 chromosomes from Mom • 23 chromosomes from Dad

  37. HUMAN LIFE CYCLE • Haploid (Monoploid) chromosome number (n): 23 • Produced by Meiosis • Homologous chromosomes separate • Each gametes contains only one member of each homologous pair

  38. HUMAN LIFE CYCLE

  39. Spermatogenesis • Meiosis consists of two consecutive nuclear divisions and the production of four daughter cells with half as many cells as a normal body cell: • Meiosis I: reduces the number of chromosomes in a cell from 46 to 23 by separating homologous chromosomes into different cells • Meiosis II: resembles mitosis in every way, except the chromatids are separated into four cells

  40. COMPARISON OF MITOSIS AND MEIOSIS IN A MOTHER CELL WITH A DIPLOID NUMBER (2N) OF 4

  41. MEIOTIC CELL DIVISIONINTERPHASE

  42. MEIOSIS I

  43. MEIOSIS II

  44. INTERNAL STRUCTURE OF TESTIS

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