Teratogenesis and the movement of ions.

There is evidence that in early embryos, mechanisms exist for the control of the movement of monovalent ions; that sodium is extruded during gastrulation and neurulation, and that in two- to three-day-old chick embryos with head abnormalities, ratios of sodium to potassium may be abnormally high. It is suggested that the origin of neural tube defects in early development may be associated with failure of control of ionic movements.