SPATIOTEMPORAL EXPRESSION GRADIENTS OF THE CARBOHYDRATE ANTIGEN CD15 (LEWIS(X)) DURING DEVELOPMENT OF THE HUMAN BASAL GANGLIA

The developmental expression pattern of the carbohydrate epitope CD15 (Lewis(chi), Le(chi)) (alpha 1-->3-fucosyl-N-acetyl-lactosamine) has b een immunocytochemically evaluated in paraffin sections within the hum an basal ganglia from 10 weeks gestation to three years after birth. A t ii weeks of gestation, CD15 (Le(chi)) positive radial glial cells we re located in the anterior and dorsal parts of the lateral ganglionic eminence. Their processes ran from the subventricular zone radially in a highly ordered Fashion to the dorsolateral margin of the caudate nu cleus and further to the lateral rim of the putamen. At 12 weeks of ge station, strands of CD15 (Le(chi)) material continued to the pial surf ace, forming a continuous CD 15(Le(chi)) positive borderline separatin g the accumbens nucleus and olfactory tubercle from the piriform corte x. At 13 weeks of gestation the dorsal putamen was completely CD15 (Le (chi)) immunoreactive along its perimeter and CD15 (Le(chi)) patches, consisting of fine granular material, appeared at the dorsolateral mar gin of the putamen at this age; while the first CD15 (Le(chi)) patches in the caudate nucleus were observed four weeks later. The matrix com partment of the caudate and dorsal putamen became gradually stained by granular CD15 (Le(chi)) positive material into which CD15 (Le(chi)) i mmunoreactive somata were embedded. The striking contrast in staining between patch and matrix compartments disappeared shortly after birth. The ventral striatum did not become immunoreactive until the last few weeks before birth. After the formation of CD15 (Le(chi)) positive pa tches in the striatum (from 12 weeks of gestation), delicate CD15 (Le( chi)) fibres, often accumulated in bundles and related to the striatal patches, became apparent coursing towards the external pallidal lamin a and the globus pallidus. Immunoreactivity in the globus pallidus its elf was transient, emerging from 16 weeks of gestation, reaching a pea k at 21 weeks of gestation and disappearing by birth. Both processes, i.e. the occurrence of CD15 (Le(chi)) striatopallidal fibres and the e merging immunoreactivity in their pallidal target, may be interrelated , so that ingrowing CD15 (Le(chi)) positive axons from the striatum pr ovoke CD15 (Le(chi)) expression in the external and internal pallidum. The variable patterns and intensities of CD15 (Le(chi)) expression ar e possibly related to periods of maturation of the striatum and the es tablishment of functional interactions within the basal ganglia. Diffe rential staining of patch and matrix in the developing neostriatum sug gests that a distinct phase of cellular adhesion or dishesion mediated by the CD15 (Le(chi)) epitope occurs during establishment of the patc h and matrix regions. (C) 1998 IBRO. Published by Elsevier Science Ltd .