Independent effects of prenatal immune activation and genetic Nurr1 deficiency on midbrain dopamine cell numbers. A, Schematic coronal brain sections delineating the ventral midbrain areas investigated with reference to bregma [adapted from The Mouse Brain in Stereotaxic Coordinates by Franklin and Paxinos (2008)]. Dopaminergic midbrain cells were quantified in sections ranging from bregma −2.92 to −3.64 mm. 1, VTA; 2a, SNc; 2b, SNr. B, Stereological estimates of TH-positive cells in the SN and VTA of adult wt and Nurr1+/− offspring subjected to prenatal poly(I:C) (POL) (2 mg/kg, i.v.) or vehicle [saline (SAL)] on gestation day 17. Stereological estimates in the SN took into account TH-positive cells in both the SNc and SNr. **p < 0.01 and §p < 0.05, signifying the main effects of genotype and prenatal treatment, respectively. N = 7 males in each experimental group; all values are means ± SEM. C, Coronal brain sections of representative SAL- or POL-exposed wt and Nurr1+/− offspring stained with anti-TH antibody. The sections highlight the SN and VTA regions as indicated by the dashed lines. Note the decrease of TH-positive cell bodies in the SN of SAL- or POL-exposed Nurr1+/− offspring (indicated by the arrowheads), and the reduction of TH-positive cells in the VTA of POL-treated wt or Nurr1+/− offspring (indicated by the white stars).