The 'cells of Rauber' are:

Options

A. Inner cell mass of blastocoel
B. Secretory cells of endometrium
C. Trophoblast cells in contact with uterine wall.
D. Terophoblast cells in contact with inner cell mass of blastocyst.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the 'cells of Rauber', which are associated with early embryonic development.

2. **Identifying the Options**: The options provided are:
- A) Inner cell mass of blastocyst
- B) Security cells of endometrium
- C) Trophoblast cells in contact with uterine wall
- D) Trophoblast cells in contact with inner cell mass of blastocyst

3. **Analyzing the Options**:
- **Option A**: Inner cell mass of blastocyst refers to the group of cells that will eventually develop into the embryo itself, but these are not the cells of Rauber.
- **Option B**: Security cells of endometrium does not relate to the cells of Rauber.
- **Option C**: Trophoblast cells in contact with the uterine wall are involved in implantation but are not specifically referred to as cells of Rauber.
- **Option D**: Trophoblast cells in contact with the inner cell mass of blastocyst are known as cells of Rauber.

4. **Conclusion**: Based on the analysis, the correct answer is option D, which states that the cells of Rauber are the trophoblast cells in contact with the inner cell mass of the blastocyst.

5. **Final Answer**: Therefore, the answer is option D: Trophoblast cells in contact with inner cell mass of blastocyst.

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