What is the sequential pattern in early embryology in animal

What is the sequential pattern in early embryology in animals that provides insights on animal evolutionary relationships?

Solution

In early embryology, cells differentiate in a sequential pattern. Initially in the blastogenetic phase the totipotent cells can modify into any cell of the body. Also during this phase, body symmetry is established and the dorsal and ventral mesoderm and segmentation are formed. Further down, the totipotent cells become pluripotent and capable of differentiating into specific cell types of the body. They form the progenitor fields which go on to become epimorphic fields in which the primordia of future organs develop by the process of organogenesis. This development in the embryological stages, from a single generalized stem cell through formation of differentiated cells to organs, is comparable to evolutionary changes one would witness in animals over generations and can provide insights on animal evolutionary relationships. The fact that the sequential pattern and the form of the embryo belonging to the same class usually bear resemblance to each other, even when the adult forms differ, can also add more insights into the evolutionary relationships of animals based on study of sequential pattern in early embryology.