Fig. 2. TH-positive MesDA neurons are lost primarily during fetal period for the SN and during postnatal period for VTA. (A) Plane of sections for analysis of TH-positive neurons in brain of E12.5 embryos. (B-G) Equivalent rostral-to-caudal sections through the midbrain of E12.5 wild-type (B,D,F) and ak (C,E,G) embryos immunostained for TH. (H,I) Coronal midbrain sections containing the SN and VTA in P1 wild-type (H) and ak (I) mice immunostained for TH. (J) Stereological analysis of TH-positive cells of the left SN and VTA in P1 wild-type and ak mice. The data are represented as the mean±s.e.m. (n=4). (K) Stereological analysis of TH-positive cells of the left SN and VTA in P21 wild-type and ak mice (n=4). A statistically significant decrease in TH-positive cell bodies was detected in the SN of P1 and P21 ak mice compared with controls (P<0.01, t-test) with no difference in the VTA. (L) Frequency of apoptotic cells revealed by TUNEL assay in the left SNc of P1 wild-type and ak mice (n=4). A statistically significant increase in the frequency of apoptotic cells was detected in the SNc of P1 ak mice compared with controls (P<0.05, t-test).