RETINOID SIGNALING AND AXIAL PATTERNING DURING EARLY VERTEBRATE EMBRYOGENESIS

There are many indications that active retinoids are regulatory signal s during vertebrate embryogenesis. Treating vertebrate embryos with re tinoids can cause teratogenic defects, including specific derangements of the main body axis. Other data show that early vertebrate embryos contain physiologically relevant concentrations of active retinoids an d express retinoid binding proteins and receptors; that knockouts of r etinoid receptors can induce homeotic defects; and that relevant devel opmental control genes are regulated by retinoid response elements. He re, we discuss the possibility that retinoids are developmental signal s which regulate axial patterning in the early vertebrate embryo.