Which of the following statements is incorrect about Leydig cells?

Options

A. They are abundant in early foetal life.
B. They gradually diminish during childhood.
C. Their numbers increase at puberty.
D. They are absent in old age.

Answer

To determine which statement about Leydig cells is incorrect, let's analyze each of the provided options step by step.

### Step 1: Understand Leydig Cells
Leydig cells are located adjacent to the seminiferous tubules in the testes and are primarily responsible for the production of androgens, including testosterone. Their activity is regulated by luteinizing hormone (LH) from the pituitary gland.

### Step 2: Evaluate Each Statement
1. **Statement 1: They are abundant in early fetal life.**
- This statement is **true**. Leydig cells are indeed present and active during early fetal development, contributing to the development of male reproductive structures.

2. **Statement 2: They gradually diminish during childhood.**
- This statement is also **true**. After fetal development, Leydig cell activity decreases during childhood as the need for androgens diminishes until puberty.

3. **Statement 3: Their number increases at puberty.**
- This statement is **true**. At puberty, Leydig cells increase in number and activity in response to rising levels of luteinizing hormone, which stimulates testosterone production.

4. **Statement 4: They are absent in old age.**
- This statement is **false**. While the number of Leydig cells may decrease with age, they are not completely absent in old age. Therefore, this statement is incorrect.

### Conclusion
The incorrect statement about Leydig cells is: **They are absent in old age.**