Which of the following is not one of the germ layers formed during gastrulation?

• A. Ectoderm
• B. Mesoderm
• C. Periderm
• D. Endoderm

Answer: (C)

Verified step by step guidance

1. Understand the concept of gastrulation: Gastrulation is a phase early in the embryonic development during which the single-layered blastula is reorganized into a multilayered structure known as the gastrula.
2. Identify the germ layers formed during gastrulation: The three primary germ layers formed are the ectoderm, mesoderm, and endoderm.
3. Define each germ layer: The ectoderm forms the outermost layer and gives rise to structures such as the skin and nervous system. The mesoderm forms the middle layer and develops into muscles, bones, and the circulatory system. The endoderm forms the innermost layer and becomes the gastrointestinal tract and other internal organs.
4. Recognize the term 'Periderm': The periderm is not a germ layer formed during gastrulation. It is a temporary embryonic layer that forms part of the developing skin but is not one of the primary germ layers.
5. Conclude which option is not a germ layer: Based on the definitions and roles of each layer, identify that 'Periderm' is not one of the germ layers formed during gastrulation.