which of the following is correct regarding embryonic development?

Options

A. Heart sound of the foetus can be heard using stethoscope usually after four week of gastation
B. First movement of foetus occurs just after 3rd month
C. Implantation occur at morula stage
D. Allantois serve as site of blood cell synthesis in foetal stage

Answer

To solve the question regarding embryonic development, we will analyze each option provided and determine which statement is correct based on the information provided in the video transcript.

### Step-by-Step Solution:

1. **Understanding Embryonic Development**:
- Embryonic development is the process that begins with fertilization and continues until childbirth. It includes various stages such as cleavage, gastrulation, and organogenesis.

2. **Evaluating the First Option**:
- The statement claims that the heart sound of the fetus can be heard using a stethoscope after 4 weeks of gastrulation.
- According to the transcript, this statement is correct because the heart begins to develop around this time, allowing the heartbeat to be detected.

3. **Evaluating the Second Option**:
- This option states that the first movement of the fetus occurs after the third month.
- The transcript clarifies that fetal movements are typically felt around the 6th month, making this statement incorrect.

4. **Evaluating the Third Option**:
- This option claims that implantation occurs at the morula stage.
- The transcript indicates that implantation actually occurs during the blastocyst stage, which is incorrect as the morula is a 60-cell stage in the fallopian tube.

5. **Evaluating the Fourth Option**:
- This option states that the allantois serves as a site for blood cell synthesis in the fetal stage.
- The transcript explains that the allantois functions primarily as an excretory organ, not for blood cell synthesis, making this statement incorrect.

6. **Conclusion**:
- After evaluating all options, the only correct statement is the first one regarding the heart sound of the fetus being detectable after 4 weeks of gastrulation.

### Final Answer:
The correct option regarding embryonic development is: **The heart sound of the fetus can be heard using a stethoscope after 4 weeks of gastrulation.**

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