MCH axons in the piriform cortex.

<p>Photomicrographs illustrating the MCH innervation of the piriform cortex (PIR) in mouse (A) and in rat (B). Insert in A is a darkfield wiev of the same section for cytoarchitectonic purposes. The indentation of this cortical field just dorsal to the lateral olfactory tract (lot) is very clear. In rat, many MCH fibers are observed in layers 1 and 2 of the dorsal piriform area, whereas very few are seen in mouse. PIR: piriform cortical field, PIRd: dorsal region of the piriform area, ORB: orbital area.