NASAL AND PHARYNGEAL ABNORMALITIES CAUSED BY THE MOUSE GOOSECOID GENEMUTATION

The Goosecoid (gsc) gene is a homeobox-containing gene expressed first in the gastrula, and later during organogenesis in development. The g sc gene transcript is found in the first and second branchial arches, frontonasal mass in its late phase of expression. We have previously s hown that targeted mutation of the mouse gsc gene leads to neonatal de ath and craniofacial defects. In this study, we performed histological studies on craniofacial phenotypes in order to elucidate the processe s underlying the neonatal death of gsc mutant mice. We found that gsc mutant mice have aplastic nasal cavities and lack the Sinus Paranasali s. We also showed that secretory olfactory glands in the basal layers are aplastic. This is suggested to be essential defects for olfaction. gsc mutant mice also show several pharyngeal phenotypes, including de fects in the pharyngeal muscles and the pharyngeal mucosa. It is there fore suggested that mutant mice develop lethal gastro-intestinal pheno types caused by defects in breathing and sucking of milk as a conseque nce of these craniofacial disorders. These results should help elucida ting the molecular genetic programs essential to the neonatal developm ent of mammals. (C) 1997 Academic Press.