Schematic illustration of typological expression of c-fos-like immunoreactivity in suprachiasmatic nucleus (SCN), and of c-fos-, NPY- and VIP-like immunoreactivity in mediobasal hypothalamus (MBH) of blackheaded bunting.

A, B (upper left panel): c-fos immunoreactivity after 4 h (left half) or 20 h (right half) of light period on the first long day in mSCN (A) and vSCN (B). C–E (upper right panel): c-fos (C), NPY (D) and VIP (E) immunoreactivity after 4 h (left half) or 20 h (right half) of light period on the first long day in the MBH. F–K: c-fos (F, G), NPY (H, I) and VIP (J, K) immunoreactivity in middle of the day (8 h after lights on; F, H, J: lower left panel) or night (4 h after lights off; G, I, K: lower right panel) in MBH of buntings in the non-migratory (left half) and migratory (right half) states. Scale bar = 1 mm (A, B); 500 µm (C–K). Abbreviations: 3V, third ventricle; CO, optic chiasma; DMH, dorsomedial hypothalamus; DSD, dorsal supraoptic decussation; GLv, nucleus geniculatus lateralis, pars ventralis; IH, inferior hypothalamic nucleus; IN, infundibular nucleus; LHA, lateral hypothalamic area; mSCN, medial suprachiasmatic nucleus; TSM, septopalliomesencephalic tract; vSCN, visual suprachiasmatic nucleus.