Sexually dimorphic expression of tac1 mRNA and Tac1 immunoreactivity in the brain. Photomicrographs in the left (A−H), middle (A’−H’) and the right (A”−H”) columns for each gender are tac1 mRNA, Tac1-immunoreactivity and a higher magnification of respective Tac1 immunoreactivities observed in the middle panels, respectively. Bar graphs in the bottom panel (I) represent the number of cells expressing tac1 counted in different brain regions of males (blue columns) and female (red columns) fish. In the anterior part of the parvocellular preoptic nucleus (PPa), there were male-dominant tac1 mRNA expression (A and B) and Tac1 immunoreactivity (A’ and B’). In the posterior part of the parvocellular preoptic nucleus (PPp) and suprachiasmatic nucleus (SC), tac1 mRNA expression was significantly higher in males (C and D), while no apparent sexual dimorphism was observed in Tac1 immunoreactivity (C’ and D’). In the ventral region of the periventricular hypothalamus (Hv), numbers of cells expressing tac1 mRNA were higher in females as compared to males (E, F, and I, P<0.01), while there was no apparent sexual morphism in Tac1 immunoreactivity (E’ and F’). In the superior raphe, more number of cells expressing tac1 mRNA were observed in males (G and G’) as compared to females (H and H’), but there was no significant difference (ns, I). Scale bars: A−H and A’−H’: 50 µm; A”−H”: 20 µm. **P<0.01. See Glossary for abbreviation.
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