(A & B) are from dissociated hippocampal cultures, (C) is from perfusion-fixed mouse cerebral cortex. Plasma membrane of astrocytes was not labeled by syntaxin 1A antibody (A). Asterisk (* in A) mark the characteristic intermediate filaments in astrocytes, and a few labels in the astroglial cytoplasm represent background noise. Label for syntaxin 1 was detected on the plasma membrane along axons (B, ab2), characterized by clusters of synaptic vesicles (SV). Label for syntaxin 1A outlined the axonal plasma membranes (C), but not the plasma membrane of dendrites (den) or the peri-synaptic astrocyte processes (astro). Scale bar = 0.1 μm.