Question

Emboly is
a. Migration of micromeres into the blastocoel
b. Migration of macromeres into the blastocoel
c. Migration of endoderm, mesoderm and notochord in the blastocoel
d. None of the above

Answer 1

Emboly is the gastrula formation simply by the invagination of the blastula wall. Emboly means the growth or the pushing of one part into another part as in the formation of the gastrula. The word emboli originated from the Greek word emboli which means insertion.

Complete answer:
- Emboly is the process of formation of a gastrula from the blastula simply by the invagination of the germ layers.
- In this process migration of three germ layers occurs in the blastocoel.
- Layers are named ectoderm, mesoderm, and endoderm.
- The migration of micromeres and macromeres into the blastocoel occurs in Sea urchin's early development stages.
- Blastocoel is a cavity filled with fluid that is formed in the blastula or blastocyst of early amphibians. It is also formed in echinoderm embryos and between the epiblast and hypoblast of reptiles and avians.

Hence, the correct answer is option (C).

Additional information:
Gastrulation is the process in embryonic development that changes the embryo from the blastula which is a single layer of cells to the gastrula containing multiple layers of cells. Mesoderm is present in animal embryos; it is a germ layer that gives rise to the specialized tissue types. Ectoderm gives rise to hairs, nails, and epiderm. Notochord forms the vertebral column. Blastocoel allows the movement of the cell during gastrulation.

Note: Emboly is the first process in gastrulation. In this process first, the cells of the blastula become the endoderm and mesoderm and then form ectoderm. The movement of cells develops a particular form and is involved in the formation of the organ in the embryo. Embryology is the process in which cells move inward to form an archenteron during gastrulation.