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

Answer

To solve the question regarding the developmental stage of the morula, we will follow these steps:

### Step-by-Step Solution:

1. **Understanding the Developmental Stages**:
- The process of human embryonic development begins with fertilization, where the male sperm and female egg unite to form a zygote.

2. **Formation of the Zygote**:
- After fertilization, the zygote undergoes a series of mitotic divisions known as cleavage. This process results in the formation of multiple cells.

3. **Cleavage and Formation of Morula**:
- As the zygote divides, it forms a 2-cell stage, then a 4-cell stage, followed by an 8-cell stage, and eventually reaches the 16-cell stage, which is referred to as the morula. The cells in the morula are called blastomeres.

4. **Transition from Morula to Blastocyst**:
- The morula continues to develop and undergoes further divisions to form the blastocyst. This is a crucial stage where implantation into the uterine wall occurs.

5. **Identifying the Correct Option**:
- Now, we need to determine the correct answer from the provided options. The morula is formed between the zygote and the blastocyst stages. Therefore, the correct option is "between the zygote and blastocyst".

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