Which of the following is correct sequence in embryo development?
(a) Cleavage, gastrulation, blastulation
(b) Blastulation, cleavage, gastrulation
(c) Clevage,blastulation, gastrulation
(d) Gastrulation,blastulation,cleavage

Options

A. Cleavage, gastrualtion, blastulation
B. Blastulation, cleavage, gastrulation
C. Clevage,blastulation, gastrulation
D. Gastrulation,blastulation,cleavage.

Answer

To determine the correct sequence in embryo development, we need to understand the processes involved: cleavage, blastulation, and gastrulation. Here’s a step-by-step breakdown of the correct sequence:

### Step 1: Understanding Fertilization
- The process of embryo development begins with fertilization, where the sperm fertilizes the ovum, leading to the formation of a zygote.

### Step 2: Cleavage
- After fertilization, the zygote undergoes cleavage. This is a series of rapid cell divisions that occur without significant growth, resulting in the formation of smaller cells called blastomeres. The cleavage stage leads to the formation of a solid ball of cells known as the morula.

### Step 3: Blastulation
- Following cleavage, the morula undergoes blastulation. During this process, the morula transforms into a hollow structure called the blastula, which consists of an inner cell mass and an outer layer of cells called the trophoblast.

### Step 4: Gastrulation
- After blastulation, the next phase is gastrulation. This is a critical stage where the blastula reorganizes into a three-layered structure known as the gastrula. The three layers formed are the ectoderm, mesoderm, and endoderm, which will later develop into different tissues and organs of the organism.

### Conclusion
- Therefore, the correct sequence of embryo development is: **Cleavage → Blastulation → Gastrulation**.

### Final Answer
- The correct option is (c) Cleavage, Blastulation, Gastrulation.

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