Correction: In the article “Three-Dimensional Structure and Composition of CA3→CA1 Axons in Rat Hippocampal Slices: Implications for Presynaptic Connectivity and Compartmentalization,” by Gordon M. G. Shepherd and Kristen M. Harris, which appeared on pages 8300–8310 of the October 15, 1998 issue, several errors appeared in Materials and Methods. The units for solutions should be mm, not mm. The infiltration was performed at room temperature (25°C), not 37°C. The paraformaldehyde concentration was 2%, not 4%.
