Very early in development, unspecialized cells have the potential to become any cell type in the body. However, as cells progress developmentally, they are more restricted in what they can become and their fates become determined—committed to developing into a particular cell type. Cell fate determination is influenced by changes in gene expression as well as by the extracellular environment. Determination is followed by differentiation—the actual changes in biochemistry, structure, and function that result in different cell types.

In an embryo, cells in a particular location will ultimately differentiate into specific cell types. In the early frog embryo, for instance, a region of cells will become skin tissue, another will become brain tissue, and another will become tissue of the notochord (a flexible rod that runs along the dorsal side of the older embryo). How early does determination occur for these cells? Would transplanting cells from one location to another change their developmental fates, implying that the cells are not yet determined, but can change depending on the environment?

In this tutorial, perform tissue transplantation experiments on frog embryos to answer this question: Is the fate of a cell in the early embryo already determined?

Click on the Next button below to begin.