GASTRULATION

"Gut Formation". Formation of the 3 "germ layers" of which the body will be constructed.

"The most important event in your life is not birth, marriage, or death, but. -gastrulation." L. Wolpert

MAIN FEATURES

1. Morphogenetic movements

2. Slowed ceil division

3. Growt is insignificant.

4. Change in energy source; increase in oxidative metabolism

5. Nuclei begin controlling activities of cells

6. New kinds of proteins being svnthesized

MAIN PROCESSES

1. Invagination

2. Epiboly

3. Delamination

4. Ingression

5. Changes in cell shape

6. Selective cell adhesion

POSITIONAL INFORMATION

How do cells know where they are in the embryo?

A clue from sea.urchin twins: animalization and vegetalization

A mechanism: Gradients