Anatomy Lecture 27

  1. Male Duct System:
  2. lecture notes
  3. Epididymis:
    • shaped like a comma about 4 cm long on the posterior
    • border of the testis
    • long coiled tubule (23 ft)
    • head: contains and receives sperm from the seminiferous tubules
    • body: lies on the posterior-lateral border of the testis and contains the highly coiled duct of the epididymis
    • tail: near the inferior border of the testis, coiling of the duct has diminished, reverses its direction and ascends into the ductus deferens, stores sperm
    • lined with pseudostratified columnar epithelium with stereocilia that regulate the composition of tubular fluid
    • wall also contains smooth muscle (peristaltic contraction move sperm through the duct)
  4. lecture notes
  5. Ductus deferens (vas):
    • approximately 45 cm long
    • extends from the tail of the epididymis to the ejaculatory ducts
    • ampulla:
    • - expanded distal portion of the vas just before it reaches the prostate
    • - joins the duct of the seminal vesicle to form the ejaculatory duct
    • - the ejaculatory ducts penetrate the prostate and empty into the urethra (lined with simple columnar)
    • lined with pseudostratified columnar epithelium with stereocilia
    • thick layer of smooth muscle
    • storage and transport of the sperm
  6. lecture notes
  7. Urethra:
    • 15 - 20 cm long
    • prostatic
    • membranous
    • penile
  8. lecture notes
  9. Accessory glands:
    • seminal vesicles:
    • prostate gland:
    • bulbourethral glands:
  10. seminal vesicles:
    • posterior surface of the bladder in front of the rectum
    • large, coiled tubular glands
    • pseudostratified, columnar or cuboidal epithelium depending on testosterone levels
    • contributes 60% of the volume of semen
    • secretion is a yellowish, viscous alkaline fluid that contains fructose, absorbic acid, coagulating enzymes called clotting proteins, prostaglandins
    • ducts join with the vas to form the ejaculatory ducts
    • sperm and seminal fluid are mixed in the ejaculatory ducts
    • sperm start to become motile
  11. lecture notes
  12. prostate gland:
    • single gland
    • consists of 30-50 tubular glands embedded in a mass of smooth muscle and connective tissue
    • produces and secretes prostatic fluid which accounts for about 1/3 of the seminal fluid
    • secretion is a milky, slightly acidic fluid
    • contains seminalplasmin which is an antibiotic
    • also contains citrate and helps the sperm to become active
    • pseudostratified columnar epithelium
  13. lecture notes
  14. bulbourethral glands:
    • “Cowper’s glands”
    • two pea-sized glands located immediately below the prostate at the base of the penis
    • secretes a thick, clear alkaline mucus that drains into the penile urethra
    • secretion is released before ejaculation to neutralize traces of acidic urine in the urethra and to lubricate the urethra and penis
    • simple columnar epithelium
  15. lecture notes
  16. Semen:
    • mixture of sperm and accessory gland secretions
    • provides for the transport, nutrition, activation and protection of the sperm
    • ejaculate volume is 2-5 ml containing 20 -100 million sperm per ml:
    • 60% from seminal vesicles, 30% from prostate, 5% from sustentacular cells, <5% from bulbourethral glands
    • clotting protein function
    • fibrinolysin functions to liquify the semen
  17. lecture notes
  18. Penis:
    • urinary and reproductive functions
    • copulatory organ
    • consists of three parts- root, body, glans
    • root: fixed portion that attaches the penis to the
    • ischium
    • body: tubular moveable portion of the penis, consists of the erectile tissues, contains the urethra
    • glans: expanded distal end, surrounds the urethral meatus
  19. lecture notes
  20. corpora cavernosa:
    • two erectile cylinders on the dorsal surface of the penis
    • makes up most of the mass of the penis
    • crura of the penis is the proximal portion of the corpora cavernosa and is attached to the bony pelvis via the ischiocavernosus muscle
  21. lecture notes
  22. corpus spongiosum:
    • surrounds the urethra
    • distal end expands to form the glans
    • proximal end is enlarged and called the bulb of the penis
    • bulb is covered by the bulbospongiosus muscle which secures it to the urogenital diaphragm
  23. lecture notes
  24. erectile tissue:
    • 3-D maze of vascular channels separated by partitions of smooth muscle
    • in the flaccid state the blood vessels are constricted and the smooth muscle partitions are tense which reduces blood flow into the erectile tissue by bypassing it
    • under parasympathetic stimulation smooth muscle relaxes, vessels dilate and blood flows into the vascular channels, engorging the cylinders of erectile tissue causing the penis to become erect
  25. lecture notes
  26. blood supply:
    • deep and dorsal arteries of the penis
    • deep dorsal vein
  27. lecture notes
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Anatomy Lecture 27