Morula is a developmental stage

Options

A. between the zygote and blastocyst.
B. between the blastocyst and gastrula.
C. after the implantation.
D. between implantation and parturition.

Explanation

### Step-by-Step Solution:

1. **Understanding the Morula Stage**: The morula is a developmental stage that occurs after fertilization. It is characterized by a solid ball of cells.

2. **Formation of the Zygote**: Fertilization occurs when a sperm cell fuses with an egg cell, forming a single-celled zygote. This is the initial stage of development.

3. **Development from Zygote to Morula**: After fertilization, the zygote undergoes several rounds of cell division (mitosis). Initially, it divides to form two cells, then four, and so on, until it reaches approximately 16 to 32 cells. This stage is known as the morula.

4. **Timing of Morula Formation**: The morula typically forms about 3 to 5 days after fertilization. It is important to note that the morula stage occurs before the blastocyst stage.

5. **Identifying the Correct Developmental Sequence**: The developmental stages are as follows:
- Zygote (single cell)
- Morula (16 to 32 cells)
- Blastocyst (a hollow structure that forms from the morula)
- Gastrula (after further development)

6. **Choosing the Correct Answer**: The question asks for the developmental stage of morula. The correct option is between the blastocyst and gastrula stages, as the morula is the stage that comes before the blastocyst.

### Conclusion:
The morula is a developmental stage that occurs between the blastocyst and the gastrula.

### Answer:
**The correct answer is: Between Blastocyst and Gastrula.**

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