Colocalization of MC4R mRNA and CRH in the PVN. A, Microscopic images of dual in situ hybridization histochemistry of MC4R mRNA (35S-labeled riboprobe, clusters of green grains) and CRH mRNA (digoxigenin-labeled riboprobe, dark purple cells). Subdivisions of the PVN: dp, dorsal parvicellular; mpd, medial parvicellular, dorsal aspect; mpv, medial parvicellular, ventral aspect; pm, posterior magnocellular. B, High magnification of microscopic images showing double-labeled cells. Black arrows indicate cells double-labeled for MC4R mRNA and CRH mRNA. White arrows indicate cells labeled for MC4R mRNA only.