Question

Explain the fate of three primary germ layers.

Answer 1

During gastrulation, the inner cell mass differentiates into ectoderm, mesoderm and endoderm. These layers give rise to the tissues and organs of the embryo.

1. Ectoderm (outer layer): Forms the epidermis and skin glands, hair, brain, spinal cord and nerves; it also contributes to structures such as the lens of the eye and inner ear.
2. Mesoderm (middle layer): Forms muscles, skeleton and notochord, heart, blood vessels, kidneys and gonads.
3. Endoderm (inner layer): Forms the lining of the digestive tract and respiratory system, and contributes to organs such as the liver, pancreas and urinary bladder.

The specialised derivatives of these three layers build the tissues and organ systems of the developing body.