Optometry Admission Test (OAT) Practice

The inner layer that develops into the gastrointestinal tract is referred to as?

1. Ectoderm

2. Endoderm

3. Mesoderm

4. Germ layer

The correct answer is: Endoderm

The inner layer that develops into the gastrointestinal tract is known as the endoderm. This embryonic layer is responsible for forming the internal structures, including the lining of the digestive tract, the liver, and the pancreas, among other organs. During the process of gastrulation in embryonic development, the endoderm differentiates into various tissues, playing a crucial role in establishing the foundational systems of the body. The ectoderm, on the other hand, is the outermost layer that gives rise to structures such as the skin and the nervous system. The mesoderm, which lies between the ectoderm and endoderm, develops into muscles, bones, the circulatory system, and several other internal structures. The reference to germ layer is more general, as it encompasses all three primary layers: ectoderm, mesoderm, and endoderm, but does not specifically identify the layer responsible for the gastrointestinal tract. Thus, identifying the endoderm as the correct answer highlights its critical role in gastrointestinal development.