EXPRESSION PATTERNS OF HOMEOBOX AND OTHER PUTATIVE REGULATORY GENES IN THE EMBRYONIC MOUSE FOREBRAIN SUGGEST A NEUROMERIC ORGANIZATION

The molecular mechanisms that control regional specification, morphoge nesis and differentiation of the embryonic forebrain are not known, al though recently several laboratories have isolated homeobox, Wnt and o ther genes that are candidates for playing roles in these processes. M ost of these genes exhibit temporally and spatially restricted pattern s of expression within the forebrain. However, analysis of the spatial patterns has been complicated because an understanding of the organiz ation of the embryonic forebrain has been lacking. This article descri bes a neuromeric model of the forebrain that is consistent with the ex pression patterns of these genes, and that provides a framework for un derstanding the morphological relationships within this complex struct ure.