Male Reproductive System

• The organs of the male reproductive system include the testes, a system of ducts, accessory sex glands, and several supporting structures, including the scrotum and the penis.
• The testes (male gonads) produce sperm and secrete hormones.
• Ducts

  • Epididymis
  • Vas deferens
  • Ejaculatory ducts
  • Urethra
• The duct system transports and stores sperm, assists in their maturation, and conveys them to the exterior.
• Epididymis (Structure and location)

  1. A tube receiving sperm from the efferent ductules
  2. 20 feet long, tightly coiled
• Functions of the epididymis

  1. Duct for sperm to pass through on the way out of the body
  2. Site for sperm maturation (1 to 3 weeks)
  3. Secretes small amounts of seminal fluid
• Vas deferens (ductus deferens) Structure and location

  1. Extends from epididymis to ejaculatory duct
  2. Has highly muscular walls
• Function of the vas deferens

  Sperm storage site
• Ejaculatory ducts (two)

  1. Formed by the union of the seminal vesicle ducts and the vas deferens
  2. Pass through the prostate gland and terminate in the urethra
• Urethra

  Serves as a passageway for urine and semen
• Seminal vesicles location

  Lower posterior bladder
• The function of the seminal vesicle

  Secrete alkaline, fructose, fibrinogen, and prostaglandins (stimulates contraction, and sperm motility)
• Prostate gland location

  Just below the bladder

  Ejaculatory ducts and urethra pass-through
• Function of the prostate gland

  Secrete alkaline fluid, clotting enzymes, and citric acid
• Bulbourethral glands(Cowper's Gland) location

  below the prostate gland
• Function of Cowper's gland

  Alkaline secretion; lubricant
• Scrotum

  Internally divided into two compartments, a testis in each
• Muscles of the scrotum

  1. Dartos fascia and muscle (Contracts to give a slight elevation of the scrotum)
  2. Cremaster muscle (Significant elevation of testes caused by its contraction, Important since sperm develop at about 3 degrees F lower than body temperature)
• Penis (external)Structure

  Three columns of erectile tissue (blood sinuses in tissue)

  1. Corpora cavernosa (Two upper cylinders)
  2. Corpus spongiosum (One lower cylinder, containing the urethra, External opening of the urethra called the external urinary meatus)
• Function of the penis

  Erection due to blood flowing into the cavernous tissue faster than it flows out
• Spermatic cords (internal)

  1. Between the scrotum and abdominal cavity, in the inguinal canal 2. Contains the vas deferens, nerves, and blood vessels in the testes
• Seminal fluid is made of secretions from the following structures:

  1. Testes and epididymis (5% of seminal fluid)
  2. Seminal vesicles (60% of seminal fluid)
  3. Prostate gland (30% of seminal fluid)
  4. Bulbourethral glands (5% of seminal fluid)
• Testes (Structure and location)

  1. In the scrotal sac
  2. Spermatic cords
• Function of the testes

  Provide access for nerves, blood vessels, and vas deferens
• Tunica albuginea

  1. Connective tissue around the testis
  2. Extends in as septa dividing the testis into 200 lobules
• Each lobule contains the following:

  1. Interstitial cells make testosterone
  2. Seminiferous tubules make sperm
• Rete testis

  1. Formed by the uniting of the seminiferous tubules
• Efferent ductules

  1. Connect the rete testis to the epididymis
• Microscopic anatomy of the testis

  1. Interstitial cells produce hormones

  2. In spaces between seminiferous tubules
• Seminiferous tubules produce sperm

  Sertoli cells -supporting cells in seminiferous tubules
• Blood-testis barrier formed by Sertoli cells

  1. Prevents the blood from contacting the sperm
  2. If blood did contact sperm, there would be a production of antibodies against the sperm. The male could be sterile.
  3. produce inhibin which stops FSH production
• Functions of the testes:

  1. Spermatogenesis (Sperm formation)
  2. Secretion of hormones by interstitial cells
• Testosterone function

  1. Promotes "maleness"
  2. Helps regulate metabolism
  3. Plays a part in fluid and electrolyte metabolism
  4. Inhibits secretion of FSH and LH by anterior pituitary
• Structure of spermatozoa: Head, middle and tail
• Head

  1) Contains chromatin

  2) Acrosome-covers anterior end and contains hydrolytic enzymes released during capacitation

  1. Enzymes-break down cervical plug
  2. Penetrate the outer covering of the egg
• Middle piece

  Has mitochondria to produce energy for locomotion
• Tail

  A flagellum used for locomotion
• Capacitation

  1. The process of making the sperm able to fertilize the ovum
  2. Occurs after ejaculation (in the vagina)
• Perineum

  1. From the symphysis pubis to the coccyx;
  2. Divided into two triangles formed by drawing a line from ischial tuberosity to ischial tuberosity
• Urogenital triangle

  1. The anterior triangle with the external genitalia
  2. Anal triangle - The posterior triangle with the anus