In leptotene, the chromosomes are

Options

A. Attached to nuclear envelope by one end
B. Attached to nuclear envelope both end directly
C. Attached to nuclear envelope both end though attachment plate
D. Both 1 and 2

Answer

To answer the question "In leptotene, the chromosomes are?", we need to understand the characteristics of the leptotene stage in meiosis.

### Step-by-Step Solution:

1. **Understanding Leptotene**:
- Leptotene is the first stage of prophase I in meiosis. It is crucial for the process of gamete formation.

2. **Chromosome Structure**:
- During leptotene, chromosomes begin to condense and become visible under a microscope. Each chromosome consists of two sister chromatids.

3. **Attachment to Nuclear Envelope**:
- In this stage, the chromosomes attach to the nuclear envelope. This attachment is facilitated by structures known as attachment plates.

4. **Telomeres**:
- The ends of the chromosomes, called telomeres, are specifically involved in this attachment. They connect to the nuclear envelope through these attachment plates.

5. **Importance of Attachment**:
- The attachment of chromosomes to the nuclear envelope is essential for the next stage of meiosis (zygotene), where homologous chromosomes will pair up.

6. **Conclusion**:
- Therefore, in leptotene, chromosomes are attached to the nuclear envelope by both ends through the attachment plates.

### Final Answer:
In leptotene, the chromosomes are attached to the nuclear envelope by both ends through the attachment plates.