Fos expression in the medial amygdala after exposure to various chemosensory stimuli in gonad-intact (a) and testosterone-replaced (b) male hamsters. Conspecific stimuli activated both anterior (MeA) and posterior (MeP) medial amygdala, while the heterospecific stimulus only activated MeA (a and b). Asterisk = significantly greater than control ( p<.03), a,b,c= significantly greater than MMU, fFGS, and mFGS respectively (p<.001 for all). CS= clean swab, HVF= hamster vaginal fluid, fFGS= female flank gland secretion, mFGS= male flank gland secretion, MMU= male mouse urine, d= dorsal subnucleus, v=ventral subnucleus.