Efferents of frontal or occipital cortex grafted into adult rat's motor cortex.

Phaseolus vulgaris leucoagglutinin (PHA-L) was used to examine the efferent connectivity of embryonic (E16) frontal (homotopic) or occipital (heterotopic) neocortical transplants placed into--or in the vicinity of--lesion cavities made in the frontal cortex of adult recipients. Homotopic transplants projected towards the host sensorimotor cortex and, in most cases, into the lateral caudate-putamen (CPu). Heterotopic transplants projected into the anterior cingulate cortex and, in most cases, distributed terminals into the medial CPu. It is suggested that embryonic neocortical tissue placed into a damaged cortical site of an adult recipient develops a pattern of efferents corresponding to its cortical origin.