Role of spleen of mammals is to

Options

A. (a) act as a haemopoietic tissue
B. (b) secrete digestive enzymes
C. (c) assist kidneys
D. (d) produce angioteninogen

Answer

### Step-by-Step Solution:

1. **Identify the Spleen's Role**: The spleen is recognized as the largest lymphoid organ in mammals. Its primary functions include blood filtration and the production of blood cells.

2. **Understand the Structure**: The spleen is composed of two main types of tissue: red pulp and white pulp. Each type has distinct roles in blood maintenance and immune function.

3. **Function of Red Pulp**: The red pulp is responsible for purifying the blood. It plays a crucial role in the destruction of old and damaged red blood cells (RBCs). This helps maintain healthy blood composition.

4. **Function of White Pulp**: The white pulp is involved in the immune response. It produces lymphocytes, a type of white blood cell (WBC), which are essential for fighting infections. Additionally, during the embryonic stage, the spleen has the ability to produce RBCs, which is known as erythropoiesis.

5. **Erythropoietic and Hemopoietic Functions**: While the spleen can produce RBCs in embryos, after birth, this function ceases, and the bone marrow takes over the production of RBCs. However, the spleen continues to produce WBCs, thus maintaining its role as a hemopoietic tissue.

6. **Conclusion**: Based on the functions of the spleen, the correct answer to the question regarding its role in mammals is that it acts as a hemopoietic tissue, particularly in the production of WBCs after birth and RBCs during the embryonic stage.