Male Reproductive system

• Male Reproductive System


  The system of organs responsible for the production and delivery of sperm and male sex hormones

  
• Testis


  • Located externally within the scrotum
  • Contains 200-300 lobules
  • Each lobule contains seminiferous tubules = site of sperm production
  • Leydig cells (outside of seminiferous tubules) produce testosterone
• Seminiferous tubules


  • Site of sperm production
  • Two types of cells within tubules: Spermatogonia (sperm stem cells) and Sertoli cells (supporting cells)
• Epididymis


  • Located externally within the scrotum with the testes
  • Site of storage and maturation of sperm cells
• Ductus deferens


  • Also called the vans deferens
  • Carries sperm from the testes into the body cavity
• Penis


  • The external sexual organ used to transfer sperm from male into female
  • Contains the urethra for urination and sperm transfer
• Seminal vesicles


  • Paired, sit at the base of the bladder
  • Produce 60% semen volume
  • Secrete alkaline fluid, fructose, prostaglandins and fibrinogen
  • Connects to the prostate gland through the ejaculatory duct
• Prostate gland


  • Single, underneath the bladder
  • Produce 30% semen volume
  • Secrete citric acid and fibrinolysin
  • Prostate gland feeds into the urethra
• Bulbourethral gland


  • Paired, at the base of penis
  • Secrete alkaline mucous prior to ejaculation to neutralise the urethra
• Spermatogenesis


  1. Production of sperm

  2. Occurs in the seminiferous tubules

  3. Initiated by follicle-stimulating hormone (FSH) and supported by testosterone
• Spermatogenesis - the process

  A single cell divides twice to produce four genetically different cells containing half the original information
• Spermatogenesis - importance of meiosis

  Only occurs in sexually reproducing organisms to produce genetically different cells
• Sperm Maturation


  1. Initial development occurs in the epididymis

  2. Capacitation = final maturation in sperm where they become mobile and develop capacity to fertilise the oocyte
• Pathway of sperm


  1. Seminiferous tubules

  2. Rete testis

  3. Efferent ductules

  4. Epididymis (maturation occurs)

  5. Ductus deferens

  6. Ejaculatory duct

  7. Prostate gland

  8. Urethra

  9. Sperm expelled from body
• SEVEN UP


  • Seminiferous tubules
  • Epididymis
  • Vas Deferens
  • Ejaculatory Duct
  • Nothing
  • Urethra
  • Penis
• Semen


  • Composed of sperm (10%) and seminal fluid (90%)
  • Seminal fluid functions to nourish sperm cells, coagulate semen, aid sperm in movement, and regulate pH
• Regulation of Testes Temperature

  1. Dartos muscle

  2. Cremaster muscle

  3. Counter-current heat exchange
• Dartos muscle


  Smooth muscle that contracts in cold temperatures to wrinkle scrotal skin, and relaxes in warm temperatures to smooth scrotal skin
• Cremaster muscle


  Skeletal muscle that contracts in cold temperatures to lift the testes closer to the pelvis, and relaxes in warm temperatures to drop testes away from the pelvis
• Counter-current heat exchange


  Testicular veins wrap around the testicular artery to increase the temperature of blood returning to the pelvis and decrease the temperature of blood descending to the testes
• Initiation of spermatogenesis


  1. Spermatogenesis begins at puberty with the secretion of gonadotropin-releasing hormone (GnRH)

  2. GnRH triggers release of luteinising hormone (LH) and follicle-stimulating hormone (FSH)

  3. LH stimulates Leydig cells in the testes to release testosterone

  4. FSH initiates spermatogenesis within seminiferous tubules

  5. Together, testosterone and FSH maintain spermatogenesis
• Testosterone


  • The main hormone secreted by the testes (Leydig cells)
  • Fundamental for spermatogenesis, development of sexual organs and development of male secondary sexual characteristics
• Overview of male reproductive hormones

  • Gonadotropin-releasing hormone (GnRH) - released by hypothalamus, stimulates release of FSH and LH
  • Luteinising hormone (LH) - released by anterior pituitary, stimulates synthesis and release of testosterone
  • Follicle-stimulating hormone (FSH) - released by anterior pituitary, initiates spermatogenesis
  • Testosterone - released by Leydig cells of testes, develops and maintains reproductive organs, supports spermatogenesis
• What is the medical term for the tube carrying sperm from the testes?

  Ductus deferens/ Vans deferens
• What is the largest cavity inside the body?

  Body cavity
• Oocyte vs Ova


  Oocyte: immature egg cells (both mature and immature) | Ova: specifically mature, released egg cells.
• Capacitation


  Final maturation in sperm where they become mobile and develop the capacity to fertilize the oocyte.