What are the three general proesses used during development to turn a single cell zygote into an adult?

 Three phases of embryonic development:
    1. Cleavage?Zygote is cleaved through cell division to produce ball of cells (morula); no accompanying cell growth so each new cell is progressively smaller. Liquid-filled cavity, called  blastocoel, develops within cell mass; now called blastula stage.

    2. Gastrulation?refers to directed cell movement, through which embryonic cells assume specific positions within embryo; yields three distinct tissue layers:
a) Endoderm?gives rise to interior tissues (lungs, liver, lining of gut and several glands).
b) Mesoderm?gives rise to tissues outside endodermal derivatives (e.g., muscle and skeletal systems, blood vessels, uterus, gonads).
c) Ectoderm?gives rise to exterior-most tissues (e.g., nervous system, skin, nails, hair, tooth  enamel).


    3. Organogenesis?a developmental process through which three germ layers give rise to organ system.
            a) Organogenesis is organized along distinct body planes, which emerge early in development; embryo is divided into two roughly equal parts (e.g., in frog embryo, dorsal and ventral planes  give rise to animal?s back and belly, anterior and posterior planes yield head and hindquarters,  respectively).
            b) Inductive processes govern organogenesis (e.g., when gastrulation is complete, notochord  develops on dorsal surface; it induces ectodermal tissues above it to form neural plate, which curls and folds over to form hollow tube, the neural tube; neural tube later differentiates into brain and spinal cord).
            c) Cell migration contributes to organogenesis (e.g., cells that break away from neural tube form neural crest cells, found only in vertebrates; these cells migrate to different locations throughout embryo and develop into very different tissues and organs, depending on their  ultimate destination: cleft lip develops when neural-crest cells forming mouth and nose fail to come together).
            d) Blocks of tissues assume specific developmental fates and give rise to specific organ systems (e.g., mesoderm tissues on either side of notochord develop into somites, which later give rise to muscles and vertebrae).