Question

Which one develops from endoderm?

• A. Nervous system, urinary bladder and eye
• B. Liver, connective tissue and heart
• C. Thymus, spinal cord and brain
• D. Liver, pancreas and thymus/thyroid

Answer 1

The correct option is D

Liver, pancreas and thymus/thyroid

After implantation, the inner cell mass (embryo) differentiates into an outer layer called ectoderm and an inner layer called endoderm. A mesoderm soon appears between the ectoderm and the endoderm. These three layers give rise to all tissues and organs seen in adults. The endoderm layer will give rise to the GI tract organs, the lining of the follicles of the thyroid gland and the epithelial component of the thymus (i.e., thymic epithelial cells) etc.