Figure 2. Pet1₂₁₀-Cre transgenic mouse line promotes somatic recombination in a non-serotonergic cell population within the raphe nuclei.

Representative low (a, b, c, d, e) and high (a’-a’’’, b’-b’’’, c’-c’’’, d’-d’’’, e’-e’’’) magnification confocal images of coronal sections of adult Pet1₂₁₀-Cre/ROSA26YFP brains, showing the distribution of YFP (green) and 5-HT (red) immunoreactivity within B8–B9 (a-a’’’), B8 (b-b’’’), B7 (c-c’’’), B6 (d-d’’’), and B1–B3 (e-e’’’) serotonergic nuclei. Boxes highlight the region of each raphe nucleus shown at higher magnification. Cells immunoreactive for both YFP and 5-HT (YFP⁺/5-HT⁺, arrowheads) or exclusively YFP but not 5-HT (YFP⁺/5-HT⁻, arrows) were detected along the antero-posterior extent of the raphe highlighting variable representativeness among the different nuclei. Scale bar: 200 µm (a–e), 30 µm (a’-a’’’, b’-b’’’, c’-c’’’, d’-d’’’, e’-e’’’).