In mammals the archenteron/primitive gut is lined with

Options

A. Ectoderm
B. Mesoderm
C. Endoderm
D. Mesoderm and endoderm.

Answer

To answer the question, "In mammals, the archenteron/primitive gut is lined with," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Archenteron**: The archenteron is the early gut formed during the gastrulation phase of embryonic development. It is a crucial structure that will eventually develop into the digestive tract.

2. **Identifying Germ Layers**: In mammals, the inner cell mass of the blastocyst differentiates into three primary germ layers: ectoderm, mesoderm, and endoderm. Each of these layers gives rise to different tissues and organs in the body.

3. **Function of Each Germ Layer**:
- **Ectoderm**: This layer forms the outermost tissues, including the skin and nervous system.
- **Mesoderm**: This layer develops into muscles, the circulatory system, and other internal structures.
- **Endoderm**: This layer is responsible for forming the inner linings of the digestive tract and respiratory systems.

4. **Formation of the Primitive Gut**: During gastrulation, the archenteron (or primitive gut) is formed from the endodermal cells. This means that the lining of the archenteron is derived from the endoderm.

5. **Conclusion**: Based on the differentiation of the germ layers and the specific role of the endoderm in forming the gut, we conclude that the archenteron/primitive gut in mammals is lined with endoderm.

### Final Answer:
The archenteron/primitive gut in mammals is lined with **C, Endoderm**.

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