Fig. 8. Bergmann glia premature differentiation is a cell-autonomous event. HDA.Cre/YFP virus was injected into Pten^loxp/loxp;Rosa26^{floxed-Stop-lacZ} at P7 and tissues were analyzed 7 or 14 days after injection. (A) Good correlation between virus infection (YFP, shown in green, upper panel) and CRE recombinase-mediated loxp excision (lacZ⁺, lower panel) in injection site. (B, a-c') Increased Bergmann fiber thickening and lateral branching (arrow) were evident one week after Pten deletion (a'). These Bergmann glia showed astrocytic morphology (arrow) 2 weeks after infection (b'). (c,c') DAPI staining performed 7 days after injection showed no apparent granule neuron migration defect within the ML; compare lacZ (+) (c') and lacZ (–) (c) regions. (C) Purkinje cell positioning was not influenced by Bergmann glia Pten deletion after P7. Normally positioned Purkinje cells (arrows) are present in lacZ (+) area when compared with the adjacent uninfected lacZ (–) area. EGL, external granule layer; ML, molecular layer; BG, Bergmann glia layer; IGL, internal granule layer. Scale bars: 50 µm.