X - body was first observed in some insects during spermatogenesis by

Options

A. Sturtevant
B. Morgan
C. Henking
D. Mendal

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the scientist who first observed the X-body during spermatogenesis in insects.

2. **Identifying the Scientist**: The correct answer is option C, Henking. He was the first to observe the X-body while studying spermatogenesis in insects.

3. **Context of the Observation**: While observing the process of spermatogenesis, Henking noted a particular nuclear structure that he termed the X-body.

4. **Description of Spermatogenesis**: Spermatogenesis involves the reductional division of diploid cells to produce haploid gametes. During this process, genetic material is segregated and distributed into the daughter cells.

5. **Observation of X-body Distribution**: Henking observed that during spermatogenesis, half of the sperm cells contained the X-body, while the other half did not. This led to the understanding that the X-body was related to sex determination.

6. **Significance of the X-body**: Although Henking did not initially understand the significance of the X-body, later research revealed that it was a chromosome involved in sex determination in insects. Specifically, it indicated that males are heterogametic (producing two types of gametes: those with and without the X chromosome).

7. **Conclusion**: Henking's observation in 1891 laid the groundwork for understanding the role of the X chromosome in sex determination, making him the first scientist to identify the X-body.

### Final Answer:
The X-body was first observed in some insects during spermatogenesis by Henking.

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