Costaining for recombinant gene expression in NMDA NR2B-containing neurons in a rat sacrificed at eight days after co-injection of pINS-TH-NFHlac/gC--ZZ+anti-NR2B and pINS-TH-NFHflag-TH/ires/aadc/gC--wt into POR cortex. Adjacent sections were costained using either mouse anti-β-gal or mouse anti-flag (detects flag-TH) and rabbit anti-NMDA NR2B, and these antibodies were visualized using rhodamine- or fluorescein-conjugated secondary antibodies, respectively. (A–C) pINS-TH-NFHlac/gC--ZZ+anti-NR2B supports β-gal expression predominantly in NR2B-containing neurons; β-gal-IR (A), NR2B-IR (B), and merge (C). Arrows, costained cells. (D–F) pINS-TH-NFHflag-TH/ires/aadc/gC--wt supports flag-TH expression in neurons that either contain or lack NR2B-IR; flag-IR (D), NR2B-IR (E), and merge (F). Arrowheads, flag-IR only. (G–I) Omitting the primary antibodies from the assay results in minimal fluorescence; rhodamine-conjugated secondary antibody-IR (G), fluorescein-conjugated secondary antibody-IR (H), and merge (I). Scale bar: 30 μm.