Reproduction

• Testis


  Site of testosterone production
• Seminiferous tubules


  Coiled collection of tubes within the testicles where spermatogenesis takes place

  
• Male reproductive system's internal organs (accessory organs)


  • Vas deferens
  • Prostate gland
  • Seminal vesicles
  • Bulbourethral (Cowper's) glands
• Vas deferens


  Transports mature sperm to the urethra during ejaculation

  
• Seminal vesicles


  Sac-like pouches that bind near the base of the bladder to the vas deferens and produce molecules that serve as energy sources for sperm, such as fructose

  
• Prostate gland


  Walnut-sized organ in front of the rectum situated below the urinary bladder that adds extra fluid to the ejaculate, which acts as sperm nourishment
• Bulbourethral (Cowper's) glands


  Pea-sized structures situated just below the prostate gland on the sides of the urethra that contain a slick, clear fluid that lubricates the urethra and neutralizes residual urine-related acidity
• Main parts of the human female reproductive system


  • Uterus
  • Ovaries

  
• Uterus


  Hosts the fetus that is developing, produces vaginal and uterine secretions, and passes sperm through to the fallopian tubes

  
• Ovaries


  Produce eggs and secrete progesterone and estrogen
• External female reproductive organs


  • Vagina
  • Labia
  • Clitoris
  • Urethra

  
• Fertilization

  1. Gametes (egg and sperm) fuse to form a zygote

  2. One set of chromosomes each in the egg and sperm

  3. Sperm binds to zona pellucida and undergoes acrosomal reactions to degrade the glycoprotein matrix and fuse with the egg plasma membrane

  4. Egg releases proteins in other places to prevent other sperm from fusing

  
• Cleavage and Blastula Stage


  1. Single-celled zygote undergoes rapid cell division to form the blastula

  2. Blastula is a spherical layer of cells around a fluid-filled or yolk-filled cavity

  3. Mammals form a blastocyst with an inner cell mass different from the surrounding blastula

  
• Gastrulation


  1. Cells in the blastula rearrange to create three layers of cells (ectoderm, mesoderm, endoderm)

  2. Ectoderm gives rise to epidermis and nervous system

  3. Mesoderm produces muscle cells and connective tissue

  4. Endoderm gives rise to columnar cells and internal organs including digestive system
• Organogenesis

  1. Organs form from the germ layers through differentiation

  2. Neural system development is a key step - neural plate rolls up to form neural tube which gives rise to brain and spinal cord

  3. Mesoderm grows into various connective tissues and is reorganized into somites which grow into muscles of ribs, lungs, and spine