Immunostaining of rat dorsal raphe neurons for SERT and TPH2. Rat dorsal raphe neurons were prepared and cultured as described in Materials and Methods, fixed, and stained with primary antibodies directed against TPH2 (A), SERT (sc-1458 in A; H-45 in B), and MAP-2 (B). Immunoreactive material was visualized with Alexa Fluor 488- and Alexa Fluor 568-conjugated secondary antibodies. Images were captured by confocal microscopy. The bottom row in B zooms in on the distal end of an axonal arborization to visualize the accumulation of SERT in bouton-like structures and at the tips of the neurite extensions. Data are representative of ≥20 neurons from ≥3 independent preparations. Scale bars, 20 μm.