ANIMALIZATION AND VEGETALIZATION OF EMBRYOS

Certain chemicals are teratogens since they cause abnormal development. Lithium chloride causes increased endodermal derivatives and trypsin or zinc chloride cause expanded ectodermal derivatives. Lithium interferes with the PIP2 to IP3 + DAG pathway of secondary messengers. Zinc may interfere with protein phosphatases or alter protein binding to DNA.

To observe these effects in sea urchin embryos: Culture fertilized embryos starting after the 2 cell stage in 18 mM LiCl in sea water (the vegetalized group) and another batch in sea water to act as controls, and another group .1 mM Zinc sulfate in sea water (the animalized group). Allow them to develop to the gastrula stage (2 days) and observe the differences under the microscope in hatching, swimming, appearance of gut.