A qualitative electron microscopic investigation of the anomalous corticofugal projections following neonatal lesions in the albino rats.

The present study confirms the suggestive evidence brought forth by the finding of Leong and Lund. Following neonatal lesion of the sensorimotor and adjacent cortex of the albino rats, the remaining intact contralateral cortex projects bilaterally to the superior colliculus, pons and spinal cord, all of which normally receive a unilateral corticofugal projection. Like the normal projections to the 3 areas studied, the anomalous projections form Gray's type I axo-dendritic relations. The terminals of the anomalous projections seem to form a more complex configuration with one axon terminal synapsing on more dendrites than is usual.