By creating Vax1/2 double knock-out mice, Dr. Lemke and colleagues found that Vax1 and Vax2 are necessary for the repression of Pax6 expression, the ventralization of the eye field, and subsequent development of the optic nerve. Dr. Lemke notes that "in many respects, the eyes represent a default differentiation pathway for the front end of the developing brain. To make an optic nerve and connect the eyes to the rest of the brain, this default pathway must be blocked and re-directed, and that's what the Vax genes do."
Genes & Development