Journal of Neuroscience, Vol 8, 892-900, Copyright © 1988 by Society for Neuroscience
Three-dimensional pattern of enkephalin-like immunoreactivity in the caudate nucleus of the cat
PM Groves, M Martone, SJ Young and DM Armstrong
Department of Psychiatry, UCSD Medical Center, 92093.
Recent anatomical investigations of the mammalian neostriatum have
uncovered discrete neurochemical zones characterized by low levels of AChE
and high levels of enkephalin-like immunoreactivity (ELI) compared with the
surrounding neostriatal tissue. These regions, termed striosomes, which
appear as patches in individual sections, have been associated with
specific afferent and efferent pathways that differ from those of the
surrounding neostriatal tissue. In the present study, the 3-dimensional
distribution of these enkephalin-rich compartments in the caudate nucleus
of the adult cat was investigated using computer- assisted 3-dimensional
reconstruction techniques. Series consisting of coronal, sagittal, and
horizontal tissue sections were obtained. In individual sections, discrete
patches of intense enkephalin-like immunoreactivity appeared against a
lighter-staining background. Three- dimensional reconstructions revealed
that these patches overlapped across sections to form a highly
inter-connected structure within the head and body of the caudate nucleus.
Several structural features were evident in these reconstructions that
appeared to be similar across animals. One consistent pattern was the
formation of enkephalin-labeled finger-like structures radiating from the
ventricular edge diagonally across the width of the nucleus. Smaller
crossbridges were seen connecting the fingers, which often resulted in the
formation of claws or rings of enkephalin-like immunoreactivity. These
elements appear to align across planes to form a lattice-like structure
outlining continuous regions of matrix. This structure may provide a basis
for the orderly interaction between the patch and matrix compartments.