Figure 1 - A, Photomicrograph of a hematoxylin-stained transverse section of the rat brain showing the site of injection into the MSA. B, Schematic representation of the location of the injection sites in the SON region (black areas). The numbers in the upper right part of each section indicate the rostrocaudal distance of that section from the bregma. LH, Lateral hypothalamic area; OX, optic chiasm; OPT, optic tract; SO, supraoptic nucleus; SOR, retro-chiasmatic supraoptic nucleus.