Organogenesis

Organogenesis is the process in prenatal development that produces organs. During organogenesis, the three germ layers formed from gastrulation: the ectoderm, endoderm, and mesoderm form the organs of the organism.

Overview

Organogenesis starts with the formation of three germ layers shortly after the formation of the gastrula. These layers are the ectoderm, mesoderm, and endoderm. Each of these layers becomes a very specific set of organs due to the specific set of genes being expressed.

Ectoderm

The ectoderm forms the outer layer of the embryo and it differentiates to form the nervous system (spinal cord, peripheral nerves and brain), tooth enamel and the skin epidermis. It also forms the lining of mouth, anus, nostrils, sweat glands, hair and nails.

Mesoderm

The mesoderm forms the middle layer and it differentiates to form the circulatory system (heart and blood vessels), skeletal system (including the muscles and cartilages), excretory system and reproductive system (including the gonads).

Endoderm

The endoderm forms the inner layer and it differentiates to form the lining of the digestive tract, the respiratory system, the urinary bladder, the digestive organs (stomach, colon, liver, pancreas), the lining of the urethra, the auditory tube and tympanic cavity, and the epithelial parts of trachea, bronchi, alveoli of lungs.

See also

• Embryogenesis
• Gastrulation
• Neurulation

Organogenesis

• 
  Germ layers
• 
  Development of the neural tube