Cerebellar afferents in normal and Weaver mutant mice

Cerebellar afferents in 3-week-old normal and homozygous Weaver mutant mice were investigated using retrograde transport of horseradish peroxidase. Almost all afferents found in other mammals were demonstrated in both normal and mutant mice of this age. Labelling in the trigeminal nuclei in both mutants and normals was found only in cases in which the ansoparamedian or uvular lobules were included in the injection site, indicating that the projection domains of mossy fiber afferent systems retain their normal boundaries in the mutants despite a lack of normal synaptic partners. Thus the neurological signs which the Weaver exhibits from about the 10th postnatal day are unlikely to depend on primary or secondary losses of cerebellar afferents or on a breakdown of the gross topographic organization of these afferents.