Which of the following is correct about the blastocyst ?

Options

A. Penetrates endometrium from its embryonic pole.
B. Consists of outer trophoblast and inner embryoblast.
C. Gets implanted along with zona pellucida.
D. Has a cavity called amniotic cavity

Answer

To determine which statement about the blastocyst is correct, let's analyze each option step by step.

### Step 1: Understand the Structure of the Blastocyst
The blastocyst is a structure formed in the early development of mammals, typically around 5 days after fertilization. It consists of two main parts:
- **Inner Cell Mass (ICM)**: This is the group of cells located inside the blastocyst that will eventually develop into the embryo.
- **Trophoblast**: This is the outer layer of cells that surrounds the inner cell mass and the fluid-filled cavity known as the blastocele. The trophoblast plays a crucial role in implantation and later forms part of the placenta.

### Step 2: Analyze Each Option
1. **Option 1: Penetrates endometrium from embryonic pole**
- This statement is incorrect. The blastocyst does not penetrate the endometrium from the embryonic pole; instead, it is the trophoblast layer that adheres to the uterine endometrium.

2. **Option 2: Cyst outer trophoblast and inner embryoblast**
- This statement is partially correct but misleading. While it correctly identifies the outer layer as the trophoblast, it incorrectly refers to the inner layer as the "embryoblast." The correct term is "inner cell mass." Therefore, this option is incorrect.

3. **Option 3: Gets implanted along with zona pellucida**
- This statement is correct. The blastocyst is initially surrounded by a protective layer called the zona pellucida, which is shed during the implantation process. The trophoblast then adheres to the endometrium for implantation.

4. **Option 4: Has a cavity called amniotic cavity**
- This statement is incorrect. The cavity within the blastocyst is called the blastocele, not the amniotic cavity. The amniotic cavity develops later in the embryo's development.

### Conclusion
After analyzing all the options, the correct statement about the blastocyst is **Option 3: Gets implanted along with zona pellucida**.

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