Method

Cells in this location ultimately become brain tissue.

Cells here ultimately become the tissue of the notochord, a stiffening rod in the embryo.

Early frog embryo with several hundred cells

Cells in this location ultimately become brain tissue.

Early frog embryo with several hundred cells

Cells here ultimately become the tissue of the notochord, a stiffening rod in the embryo.

¡Tissue destined to become part of a tadpole's skin is cut from an early embryo (donor) and transferred to another early embryo (host).

¡Tissue destined to become part of a tadpole's skin is cut from an early embryo (donor) and transferred to another early embryo (host).

Plasma Membrane Images
RESULTS Brain

a The donor tissue becomes brain tissue.

a The donor tissue becomes brain tissue.

The donor tissue becomes notochord tissue.

Notochord

Notochord

The donor tissue becomes notochord tissue.

Conclusion: Cell fates in the early embryo are not determined, but can change depending on the environment.

environment and the contents of the cell on the cell's genome. Determination is not something that is visible under the microscope—cells do not change their appearance when they become determined. Determination is followed by differentiation, the actual changes in biochemistry, structure, and function that result in cells of different types. Differentiation often involves a change in appearance as well as function. Determination is a commitment; the final realization of that commitment is differentiation.

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Essentials of Human Physiology

Essentials of Human Physiology

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