Immunofluorescence showing M6a immunoreactivity in the stratum lucidum (str.luc.) of the hippocampus (A, C) and in the infralimbic cortex (B, D) as revealed by confocal microscopy.

<p>A: M6a (red) and synaptophysin immunoreactivity (green) in the stratum lucidum. Note that the giant mossy fiber terminals (mft) which are strongly synaptophysin positive surround the unlabeled dendrites (d) of the CA3 pyramidal neurons. B: M6a (red) and synaptophysin immunoreactivity (green) in the infralimbic cortex; axons (ax) are M6a immunopositive, dendrites (d) are unlabeled. Note that there is occasional colocalization (yellow) of M6a and synaptophysin in the axonal terminals that surround the unlabeled soma of the pyramidal neuron (pyr). C: M6a (red) and MAP-2 immunoreactivity (green) in the stratum lucidum. Note that the dendrites (d) of CA3 pyramidal neurons which are strongly MAP-2 positive are not labelled by the M6a antibody. D: M6a (red) and MAP-2 immunoreactivity (green) in the infralimbic cortex. Note that there is no colocalization of M6a and MAP-2 in the axons/axonal terminals (ax) that surround the MAP-2 immunopositive soma of the pyramidal neurons (pyr).