KOR mRNA in ARC. Representative dark- (A) and bright-field (B) photomicrographs of a hypothalamic section at the level of the middle ARC hybridized with antisense probe to ovine KOR mRNA. High-power dark- (C) and bright-field (D) photomicrograph of ARC cells expressing KOR (arrows) from outlined area (white box) in panel A. E and F, Representative dark-field photomicrographs showing the distribution of KOR mRNA-containing cells in the rostral (E) and caudal (F) ARC. Scale bar (B, E, and F), 500 μm; (D), 100 μm. cARC, caudal ARC; fx, fornix; mARC, middle ARC; me, median eminence; MRe, mammillary recess of the third ventricle; rARC, rostral ARC; 3v, third ventricle.