Fig. 5. Interneuron migration to the cerebellar cortex is impaired in treated MBP-TK mice. Cerebellar sections from 3-(A,B) and 6-day-old (C-F) wild-type (A,C,E) and MBP-TK (B,D,F) treated mice were analyzed using a PAX2 antisense riboprobe (A-D). (E,F) Serial sections from the same 6-day-old treated mice were immunostained with an anti-PAX2 antibody (E, wild type; F, MBP-TK). In the wild type, migrating PAX2-positive cells are found in the white matter tract (arrowheads; A,C,E). In MBP-TK cerebella, a strong reduction in migrating PAX2-positive cells (arrowhead in F) is observed (B,D,F). (G,H) In situ hybridization using a GAD67 riboprobe. Insets show higher magnification of the ML of each section. (I,J) Immunofluorescence using an anti-parvalbumin antibody on cerebellar sections of 21-day-old wild-type and MBP-TK (1-20d) treated mice. (G) In wild-type mice, the GAD67 probe labels Purkinje cell bodies and interneurons localized in the ML and in the IGL. (H) In MBP-TK mice, only the Purkinje multicellular layer and interneurons in the IGL can still be detected. Higher magnification of the ML (insets in G,H) shows the presence and absence of GAD-positive interneurons in wild-type and MBP-TK mice, respectively. (I) Basket and stellate cells (arrowheads) visualized by anti-parvalbumin immunostaining within the ML of the wild-type cerebella. (J) Interneurons are absent in the ML of the MBP-TK cerebella. Arrowhead in J indicates parvalbumin-positive interneurons. Scale bars: 170 µm (A-D); 70 µm (E,F); 200 µm (G,H); 50 µm (I,J).