The solid mass of cells formed at the end of cleavage of mammalian egg is

Options

A. Blastula
B. Morula
C. Blastocyst
D. Blastodisc

Explanation

To answer the question regarding the solid mass of cells formed at the end of cleavage of a mammalian egg, we can break down the process step by step:

### Step-by-Step Solution:

1. **Fertilization**: The process begins with the fertilization of the egg by the sperm, resulting in the formation of a zygote.

2. **Zygote Formation**: The zygote is the single cell that results from the fusion of the sperm and egg nuclei.

3. **Cleavage Process**: After the zygote is formed, it undergoes a series of mitotic divisions known as cleavage. This process increases the number of cells without increasing the overall size of the embryo.

4. **Cell Division Stages**: During cleavage, the zygote divides into two cells (2-cell stage), then into four cells (4-cell stage), and subsequently into eight cells (8-cell stage).

5. **Formation of Morula**: At the end of the cleavage process, the solid mass of cells that is formed is called the morula. This stage typically consists of 16 to 32 cells and resembles a mulberry, hence the name "morula."

6. **Transition to Blastocyst**: Following the morula stage, the next developmental stage is the formation of the blastocyst, which includes an outer layer called the trophoblast and an inner cell mass.

### Final Answer:
The solid mass of cells formed at the end of cleavage of a mammalian egg is called the **morula**.