Lack of Nigral Dopaminergic Neuronal Degeneration in ROSA26-αSyn Mice. Stereological analysis of TH-positive and Nissl-positive neurons in the substantia nigra pars compacta of male ROSA26-αSyn mice with or without Cre expression. (A) Example of immunohistochemical staining for TH with Nissl counterstain on coronal midbrain sections highlighting the substantia nigra region from 12 month-old ROSA26-αSyn119+/+/TH-Cre mice and their ROSA26-αSyn119+/+ littermate controls. (B-E) Stereological analysis revealing a normal number of TH-positive and Nissl-positive neurons in the substantia nigra pars compacta (SNpc) of 10–12 month-old ROSA26-αSyn119+/-/nestin-Cre (B), ROSA26-αSyn119+/+/TH-Cre (C), ROSA26-αSyn-A53T+/-/nestin-Cre (D) and ROSA26-αSyn-A53T+/+/TH-Cre (E) mice compared to their age-matched non-floxed ROSA26-αSyn littermates (Cre -). Data are expressed as the mean ± SEM (n = 4–6 mice per genotype). There are no significant differences (p > 0.05) between genotypes following statistical analysis by unpaired, two-tailed Student's t test.