Musculotopic organization of the facial nucleus of the reeler mutant mouse.

The migration of facial motoneurons is affected by the reeler gene, and the facial nucleus of the reeler mutant is cytoarchitecturally abnormal. The present study was undertaken to compare the musculotopic organization of the reeler facial nucleus with that of the normal mouse by the retrograde horseradish peroxidase method. In the normal mouse, motoneurons supplying the nasolabial muscle were located in the lateral and dorsolateral subnuclei, those supplying the posterior auricular muscle in the ventromedial and dorsomedial subnuclei, those supplying the mentalis/platysma muscle in the ventral intermediate subnucleus of the facial nucleus, and those supplying the posterior belly of the digastric muscle in the accessory facial nucleus. This musculotopic representation on the main facial nucleus and accessory facial nucleus also appears in the reeler mouse. The musculotopic representation of the facial nucleus of the reeler mouse is thus identical to that of the normal mouse in spite of the former's cytoarchitectonic abnormalities.