Figure 7.

KIF21B mRNA is predominantly localized to the cell body. In situ hybridization was performed on adjacent sagittal sections through the adult hippocampus using antisense riboprobes for KIF21A (A and E), KIF21B (B, F, and H), or MAP2 (C, G, and I), or a sense riboprobe for KIF21B (D; this and all other sense probes produced no specific signal). At low magnification (A–D), KIF21A (A) and KIF21B (B) hybridization signal can be observed primarily in the pyramidal cell bodies of the CA fields and in the granule cell bodies of the dentate gyrus. In contrast, MAP2 mRNA, which is known to be transported to the dendrite, is detected both in the cell bodies and in the adjacent molecular layer (m) that contains pyramidal cell dendrites. This difference in localization is confirmed at higher magnification (E–I). While radial dendrite-like labeled structures are clearly visible using the MAP2 riboprobe (G and I, arrowheads), no such labeled structures are observed using either KIF21A (E) or KIF21B (F and H) riboprobes. Labeling is confined predominantly to the pyramidal cell body layer (p). Bars: 700 μM (A–D); 150 μM (E–G); and 10 μM (H and I).