Unipolar neurons with an axon and no dendrite are present in :

Options

A. Embryos
B. Dorsal root ganglia of spinal cord
C. Brain
D. Retina

Explanation

**Step-by-Step Solution:**

1. **Understanding Unipolar Neurons**: Unipolar neurons are characterized by having a single process extending from the cell body. This process is known as a neurite, which can develop into branches that form dendritic or axonal processes later in development.

2. **Identifying the Options**: The question provides four options:
- Embryos
- Dorsal root ganglia of spinal cord
- Brain
- Retina

3. **Analyzing Each Option**:
- **Embryos**: In early development stages, unipolar neurons are present, which can have an axon but no dendrites.
- **Dorsal Root Ganglia of Spinal Cord**: These typically contain pseudounipolar neurons, which have a single process that divides into two branches, one functioning as an axon and the other as a dendrite.
- **Brain**: The brain contains various types of neurons, but unipolar neurons are not commonly found here.
- **Retina**: The retina contains bipolar and ganglion cells, but not unipolar neurons.

4. **Conclusion**: Based on the analysis, unipolar neurons with an axon and no dendrite are primarily found in the early stages of embryos.

5. **Final Answer**: Therefore, the correct answer is **Embryos**.

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