Which of following sequence followed in human embryology is correct ?

Options

A. Syngamy `to` II meiotic division completed `to` Plasmogamy `to` Karyogamy
B. II–meiotic division completed `to` syngamy `to` plasmogamy `to` karyogamy
C. Syngamy `to` Plasmogamy `to` II meiotic division completed `to` Karyogamy
D. Syngamy `to` plasmogamy `to` karyogamy `to` II meiotic division completed

Answer

To determine the correct sequence followed in human embryology, we need to understand the processes involved in fertilization and subsequent events. Here’s the step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Syngamy**: The first step in human embryology is syngamy, which is the fusion of the male and female gametes. This process is commonly referred to as fertilization. When the sperm penetrates the egg, syngamy occurs.

2. **Plasmogamy**: After syngamy, the next step is plasmogamy. This is the fusion of the cytoplasm of the male and female gametes. At this stage, the nuclei of the gametes remain separate; only their cytoplasmic contents mix.

3. **Second Meiotic Division**: Following plasmogamy, the female gamete undergoes the second meiotic division (meiosis II). This division results in the formation of a polar body and the mature ovum. The polar body is extruded, while the ovum retains its nucleus.

4. **Karyogamy**: The final step is karyogamy, which is the fusion of the male and female nuclei. This occurs after the female nucleus has completed meiosis II and is ready to combine with the male pronucleus.

5. **Final Sequence**: Therefore, the correct sequence in human embryology is:
- Syngamy (fertilization)
- Plasmogamy (fusion of cytoplasm)
- Second meiotic division (meiosis II of the female gamete)
- Karyogamy (fusion of nuclei)

### Conclusion:
The correct sequence followed in human embryology is:
1. Syngamy
2. Plasmogamy
3. Second meiotic division
4. Karyogamy

The correct answer to the question is option number 3.