Journal of Neuroscience, Vol 4, 141-150, Copyright © 1984 by Society for Neuroscience
Connections made by transplants to the cerebral cortex of rat brains damaged in utero
MK Floeter and EJ Jones
Homografts consisting of pieces of neocortex or dissociated cortical cells
were transplanted from fetal rats into the cortex of newborn, microcephalic
hosts. The cortex of the hosts lacked cells of the superficial layers, as a
result of prenatal administration of a cytotoxic drug methylazoxymethanol.
Grafts exhibited an internal organization with a tendency to form a
molecular layer, and alternating cell and fiber zones, although these were
not consistently oriented with respect to the host cortex. Both pyramidal
and nonpyramidal cells survived. Some grafts were shown to receive callosal
connections. Axonal outgrowth from transplanted neurons to several host
brain areas was demonstrated with retrograde tracers. Outgrowth occurred
not only to the contralateral cortex, in which the host's own callosal
projection was deficient, but also to the thalamus and spinal cord, in
which the host projection was intact. Thus, grafted fetal cortex is capable
of making connections in the methylazoxymethanol-damaged host, but the
pattern of connections made is not influenced by host deficiencies.