In devalopment, Eustachian tube is

Options

A. Ectodermal
B. Mesodermal
C. Endodermal
D. Both mesodermal and endodermal.

Answer

To solve the question regarding the developmental origin of the Eustachian tube, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Eustachian Tube**: The Eustachian tube, also known as the auditory tube, connects the middle ear to the nasopharynx. Its primary function is to equalize pressure in the middle ear and to allow drainage of secretions.

2. **Identify the Germ Layers**: In embryonic development, there are three primary germ layers: ectoderm, mesoderm, and endoderm. Each of these layers gives rise to different structures in the body.

3. **Determine the Origin of the Middle Ear**: The middle ear, where the Eustachian tube is located, is known to develop from the endoderm. This is crucial because the origin of the Eustachian tube is directly linked to the development of the middle ear.

4. **Analyze the Options**:
- A) Ectodermal: This is incorrect as the ectoderm primarily gives rise to structures like the skin and nervous system.
- B) Mesodermal: This is also incorrect as the mesoderm is responsible for structures such as muscles, bones, and the circulatory system.
- C) Endodermal: This is the correct option since the Eustachian tube originates from the endoderm.
- D) Both mesoderm and endodermal: This option is incorrect as the Eustachian tube is solely derived from the endoderm.

5. **Conclude the Answer**: Based on the above analysis, the Eustachian tube is endodermal in origin. Therefore, the correct answer is option C.

### Final Answer:
The Eustachian tube is endodermal in origin (Option C).

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