HOMEOBOX GENES IN THE DEVELOPING MOUSE-BRAIN

Any list of past and recent findings on vertebrate brain prenatal deve lopment would have to include the fundamental roles of homeobox genes, the genes encoding the nuclear regulatory homeodomain proteins. The d iscovery of homeobox genes and their involvement as master regulatory elements in programing the development of an embryo into a complete ad ult organism has provided a key to our understanding of ontogenesis. A lso, the correlation of mouse developmental mutants and their correspo nding human syndromes with mutations in homeobox genes has provided fu rther evidence for the fundamental role of homeobox genes during the v ertebrate brain embryonic development. Here, we review the expression patterns and the phenotypes of gene mutations that implicate a large r epertoire of mouse homeobox genes in the specification of neuronal fun ctions during brain embryogenesis.