Fig. 5. Purkinje cell death in the neonatal cerebellum. (A) Apoptotic cell counts in wt versus mutant cerebella at P0 (n=3, ±s.d.) immunostained for active Caspase 3, reveal a significant increase in cell death in the null. (B-D) Double immunofluorescence, as labeled (ovl: overlay). The majority of active Caspase 3-positive cells are ectopically positioned near the VZ and are CaBP-positive (arrows in B-D), while cell debris positive for active Caspase 3 is CaBP-negative (arrowheads in B-D). (F) In the null cerebellum, activated caspase-3-positive cells are clustered near the VZ (wt control in E). (G) Dying cells located ventrally are double-positive for active Caspase 3 and lacZ. (I,L,M) An increased number of active Caspase 3 and lacZ-double-positive cells are observed in the mutant cerebellar cortex (arrows, controls in H,J,K). Scale bars: in D, 100 µm for B-D; in M, 250 µm for E,F,H-M; in G, 150 µm for G.