State the sequential stages from zygote to embryo to foetus. Discuss them in detail.

Explanation

### Step-by-Step Solution

1. **Formation of Zygote**:
- The process begins with fertilization, where a male sperm cell fuses with a female egg cell. This fusion results in the formation of a zygote, which is a single-celled organism.
- The zygote contains a total of 46 chromosomes, with 23 inherited from the sperm and 23 from the egg. This genetic material is crucial as it determines the genetic makeup of the future individual.
- The zygote typically survives for about 24 hours before it begins to divide.

2. **Development of Embryo**:
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