A, Photomicrograph of a rat brain coronal section representing a retrograde tracer injection site in medial parvicellular region of the paraventricular hypothalamic nucleus (PaMP; green; Case 6), at 1.7 mm posterior to bregma. B, Similar depiction of retrograde tracer injection in the rostral region of the nucleus raphe pallidus (RPa; red; Case 47), at 11.0 mm posterior to bregma. 3v, Third ventricle; RMg, nucleus raphe magnus; Py, pyramidal tracts; ml, medial lemniscus. Scale bars, 200 μm .