RT Journal Article SR Electronic T1 Pattern Deformities and Cell Loss in Engrailed-2Mutant Mice Suggest Two Separate Patterning Events during Cerebellar Development JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 7881 OP 7889 DO 10.1523/JNEUROSCI.17-20-07881.1997 VO 17 IS 20 A1 Barbara Kuemerle A1 Hadi Zanjani A1 Alexandra Joyner A1 Karl Herrup YR 1997 UL http://www.jneurosci.org/content/17/20/7881.abstract AB Null alleles of the mouse Engrailed-2 gene, a molecular homolog of the fly gene engrailed, have demonstrable effects on the anteroposterior (A/P) patterning of cerebellum as reflected in the disruption of the normal process of foliation of the cerebellar cortex and the alteration of transgene expression boundaries in the adult. Engrailed-2 also affects the transient mediolateral (M/L) pattern of En-1and Wnt-7b expression seen in late embryogenesis. We have examined three markers of cerebellar compartmentation inEn-2 mutant mice: the Zebrin II and Ppath monoclonal antibodies and the transgene L7lacZ. InEn-2 mutants, the normal temporal pattern of expression is preserved for all three markers, although the size and spatial location of various bands differ from those of the wild type. Unlike the foliation abnormalities, the M/L pattern disturbances we have found occur in nearly all cerebellar regions. Cell counts reveal that all major cell types of the olivocerebellar circuit are reduced by 30–40%. We propose that these results are best explained by a model in which the Engrailed-2 gene is involved in the early specification of the cerebellar field including the number of progenitors. Because each of these progenitors gives rise to a clone of defined size, Engrailed-2 helps specify adult cell number. We further postulate that the configuration of the seven Zebrin bands as well as the shapes and locations of the cerebellar lobules are set up by a second patterning event that occurs after neurogenesis is complete.