amorphic allele - genetic evidence
abnormal neuroanatomy
lethal
lethal - all die during embryonic stage
some die during embryonic stage
central nervous system
MP1 precursor
VUM precursor
CNS defect: specific alterations in the pattern of precursors that give rise to the 2 MP1 progeny, ventral unpaired median neurons and the specialized ectodermal cells, the midline ectodermal cells (MEC).