Induction: Cell + Tissue Signaling

You identify cells that normally make nervous system tissue in a frog embryo. You transplant them into a region that normally makes skin. As the embryo develops, the transplanted cells contribute to the skin. The transplanted cells were:

Not determined

Transplantation of dorsal lip induces…

A second embryonic axis

The transplanted dorsal lip cells were:

Determined

You observed that the cells surrounding the transplant also contributed to the new axis. Those surrounding cells were:

Not determined

Inductive signals can be…

Diffusible or contact-dependent

Necessary

A particular interaction is required for determination + differentiation to occur.

Sufficient

A particular interaction is enough to trigger determination + differentiation.

Goosecoid mRNA induces a second axis. This experiment suggests that goosecoid is —- for development of an axis.

Sufficient

What ensures alignment of lens + sensory structures in vertebrate eye?

Induction

• Transplant experiments:

• Remove optic cup + lens doesn’t form

• Move optic cup elsewhere + lens forms there

• Remove lens vesicle + retina doesn’t form

If a developing lens from a surface fish is transplanted to the right side of a —-, an eye develops on the right side of the —-.

Cave fish

If a developing lens from a cave fish is transplanted to the right side of a —-, an eye fails to develop on the right side of the —-.

Surface fish

The defect in inductive signaling that results in the loss of eyes likely stems from:

A defective signal from the lens.