Chapter 28 Notes
The Male Reproductive System

Seminiferous tubules and Spermatogenesis

1. Scrotum

• sac-like extension of the abdominal wall
• a few degrees lower than body temperature for sperm viability

2. Testes

• covered by a thick capsule, tunica albuginea
• descent through inguinal canal shortly before birth
•  the tunica vaginalis is the outpocketing of peritoneum around testes
• cryptorchidism:  testes fail to descend
•  inguinal hernia:  enlargement of the inguinal canal
• tunica albuginea divides testes into lobules
• lobules contain convoluted seminiferous tubules undergoing spermatogenesis
  - lined with stratified epithelium to produce sperm continuously
  - spermatogonia stem cells at basement membrane divide by mitosis
  - primary spermatocytes      (2n) undergo first meiotic division
  - secondary spermatocytes undergo second meiotic division
  - spermatids    (n) develop into sperm with 23 chromosomes
• Sperm maturation process depend on Sertoli cells
  - nourish and remove wastes
   - spermatogenesis influenced by FSH

• Testosterone
  - steroid hormone, acetyl coenzyme A or cholesterol derivative
  - secreted by interstitial cells of  Leydig
  - secretion stimulus 1. hypothalamus releasing factor
                                2. pituitary gland Leutenizing hormone
  - action: binds onto receptor protein in cytoplasm and activates genes in cell nucleus
                                1. hair follicles
                                2. enlargement of larynx
                                3. enlargement of muscles fibers
                                4. calcium deposits in bones and growth
                                5. protein anabolism 
                                6. secretions of sebaceous glands
                                7. final maturation of sperm

Spermatic Ducts and Accessory Structures

3. Epididymis

• coiled tubes posterior to testes
• pseudostratified columnar cells
• sperm are stored and develop motility

4. Ductus (vas deferens)

• 18" tube extending through inguinal canal into pelvic cavity and around the bladder
• part of spermatic cord
• sperm stored in dormant state until ejaculation

5. Ejaculatory duct

• vas deferens unites into single duct
• receives portion of semen from the seminal vesicles

6. Urethra

• common duct for urine and semen
• three portions
  - prostatic urethra lies within the prostate gland
  - membranous urethra passes the pubic bone
  -  penile urethra lies within the corpus spongiosum of penis

7. Histology online

8. Accessory structures

• Seminal vesicles - 60% volume
  - paired leaf-like glands behind the bladder
  - secretes alkaline, fructose rich semen into ejaculatory duct
• Prostate gland - 25% volume
  - chestnut shaped, inferior and behind bladder
  - secretes a thin milky acid phosphatase semen into the prostatic urethra
  - prostatic hypertrophy in older men compresses the urethra making voiding difficult
• Cowper's gland
  - pea sized, inferior to prostate
  - secrete alkaline mucus into penile urethra

9. Penis

• consists of three spongy masses of blood sinuses, erectile tissue
• corpora cavernosa, two dorsal sinuses
• corpus spongiosum, ventral mass contains the penile urethra

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