Evolution

Embryology is the study of the development and and pathways of embryos. An embryo is the unborn, or unhatched, animal young in its earliest phases.

Many embroys for different organisms look quite alike in their eraly stages of development. This is because the same groups of embryotic cells develop, in the same order, to produce the tissues and organs of all vertebrates. These common cells and tissues, growing in similar ways, produce the homologous structure discussed earlier. The embryos are very similar until the ancient genes indicate what should happen to the embryo and how to diferenciate the embryos from others.