Which of the following cells of blastocyst acts as a precursor of the embryo ?

Options

A. Trophoblast
B. Inner cell mass
C. Stem cells
D. Both (B) & (C)

Answer

To solve the question "Which of the following cells of the blastocyst acts as a precursor of the embryo?", we will analyze the options provided and understand the roles of the cells in the blastocyst.

### Step-by-Step Solution:

1. **Understanding the Blastocyst Structure**:
- The blastocyst is a structure formed in the early development of mammals, typically at the 64-cell stage.
- It consists of two main components: the inner cell mass (ICM) and the outer layer of cells known as the trophoblast.

2. **Identifying the Inner Cell Mass (ICM)**:
- The inner cell mass is located at one pole of the blastocyst and is crucial for the development of the embryo.
- The cells in the inner cell mass have the ability to undergo unlimited symmetrical divisions without differentiating.

3. **Role of the Inner Cell Mass**:
- The inner cell mass contains stem cells, which are undifferentiated cells capable of developing into any tissue or organ in the body.
- Therefore, the inner cell mass acts as a precursor to the embryo, as it will eventually give rise to all the different cell types that make up the organism.

4. **Understanding the Trophoblast**:
- The trophoblast is the outer layer of cells that will eventually form the chorion, which is part of the placenta.
- While important for implantation and supporting the embryo, the trophoblast does not contribute to the formation of the embryo itself.

5. **Conclusion**:
- Based on the above analysis, the correct answer to the question is that the inner cell mass acts as a precursor of the embryo and is also associated with stem cells.
- Therefore, the correct option is both B (inner cell mass) and C (stem cells).

### Final Answer:
The cells of the blastocyst that act as a precursor of the embryo are both B (inner cell mass) and C (stem cells).

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