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How does organogenesis transform groups of embryonic cells into organs?
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Animal development
The embryos of many animals appear similar to one another in the earliest stages of development and progress into their specialized forms in later stages.
Organogenesis is the series of integrated processes that transforms an amorphous mass of embryonic cells into structurally and functionally complete organs. This transformation involves coordinated cell movement and cell differentiation, where immature cells develop into specialized types.12
During this process, germinal layersâsheets of cellsâform organ rudiments through several mechanisms:3
- Folding: A layer may groove or fold, closing into a tube that later subdivides.3
- Pocketing: A layer may produce a depression or vesicle that can branch, a common method for developing glands and lungs.3
- Thickening and Detachment: Localized thickenings in an epithelial sheet can detach to form solid structures or vesicles.3
- Mesenchymal Formation: Cells may lose their connections to become mesenchyme, a mass of loose cells that can condense into structures like muscles or skeleton.3
These processes are often guided by embryonic induction, where specific regions of the embryo emit signals that influence the developmental path of neighboring cell groups. Concurrent with organogenesis is histogenesis, the formation of the specific tissues that comprise the organ.431