Correct sequence of human embryonic development is

Options

A. Blastocoel-gastrocoel-neural crest-notochord
B. gastrocoal-blastocoel-notochord-neural crest
C. gastrocoel-blastocoel-neural crest-notochord
D. blastocoel-neural crest-gastrocoel-notochord

Explanation

To answer the question regarding the correct sequence of human embryonic development, we need to understand the stages that an embryo goes through. The correct sequence is as follows:

1. **Fertilization**: The sperm fertilizes the egg, forming a zygote.
2. **Cleavage**: The zygote undergoes a series of mitotic divisions, leading to the formation of a solid ball of cells known as the morula.
3. **Morula**: The morula is a compact mass of cells that eventually transforms into a hollow structure.
4. **Blastula**: The morula develops into the blastula, which is characterized by the formation of a fluid-filled cavity called the blastocoel.
5. **Gastrula**: The blastula undergoes gastrulation, leading to the formation of the gastrula. This stage involves the formation of the gastrocoel (primitive gut) and the differentiation of three germ layers: ectoderm, mesoderm, and endoderm.
6. **Neural Crest Formation**: Following gastrulation, the neural crest cells develop from the ectoderm.
7. **Notochord Formation**: The notochord, a rod-like structure that provides support, forms from mesodermal cells.

Thus, the correct sequence of human embryonic development is:
1. Morula
2. Blastula
3. Gastrula
4. Neural Crest
5. Notochord

**Final Answer**: Morula → Blastula → Gastrula → Neural Crest → Notochord