Notochord is

Options

A. Endodermally derived structure, formed on the dorso ventral side
B. Ectodermally derived structure, formed on the dorsal side
C. Mesodermally derived structure, formed on the dorsal side
D. Mesodermally derived structure, formed on the ventral side

Answer

**Step-by-Step Solution:**

1. **Understanding the Notochord**: The notochord is a flexible rod-like structure that plays a crucial role in the development of chordates. It provides skeletal support and is involved in the development of the nervous system.

2. **Origin of the Notochord**: The notochord is derived from the mesoderm, which is one of the three primary germ layers in the embryo (the others being ectoderm and endoderm).

3. **Location of the Notochord**: The notochord is formed on the dorsal side of the embryo during development. This means it is located towards the back of the organism.

4. **Classification of Organisms**: Organisms that possess a notochord at some stage of their life cycle are classified as chordates. In contrast, those that do not develop a notochord are classified as non-chordates.

5. **Evaluating the Options**:
- **Option A**: "Notochord is endodermally derived" - This is incorrect because the notochord is not derived from the endoderm.
- **Option B**: "Notochord is ectodermally derived" - This is also incorrect as the notochord is not derived from the ectoderm.
- **Option C**: "Notochord is mesodermally derived structure formed on the dorsal side" - This is correct since the notochord is indeed mesodermal and located on the dorsal side.
- **Option D**: "Notochord is mesodermally derived structure formed on the ventral side" - This is incorrect because, although it is mesodermally derived, it is not located on the ventral side.

6. **Conclusion**: Based on the analysis of the options, the correct answer is that the notochord is a mesodermally derived structure formed on the dorsal side.

**Final Answer**: C. Mesodermally derived structure formed on the dorsal side.

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