THE ROLE OF POLYSIALIC ACID IN MIGRATION OF OLFACTORY-BULB INTERNEURON PRECURSORS IN THE SUBVENTRICULAR ZONE

Transplantation studies have been used to show that tangential migrati on of olfactory bulb interneuron precursors is retarded in NCAM-mutant mice, and that this defect reflects loss of NCAM polysialic acid (PSA ). In contrast, radial migration of cells within the bulb did not requ ire PSA. Reciprocal transplantations between wild-type and mutant mice have revealed that the mutation affects the in vivo migration environ ment in the subventricular zone, and not movement of individual cells. However, in vitro migration of the cells into a PSA-negative collagen matrix environment was also PSA-dependent. The surprisingly similar r esults obtained in the in vivo and in vitro environments is consistent with the observation that migration of subventricular cells occurs as streams of closely apposed cells in which the PSA-positive cells appe ar to serve as their own migration substrate.