OLE-lacZ and OLEa-lacZ transgenes are predominantly expressed in oligodendrocytes.

(A) The transgenic constructs consisting of OLE or OLEa, the minimal Hsp68 promoter (hsp68), the lacZ marker gene (lacZ) and a SV40 polyA signal (pA) are schematically shown. (B) Five founders were obtained after pronucleus injection of OLE-lacZ and OLEa-lacZ that inherited the transgene to their progeny and were expanded to lines. Three of them (OLE#4, OLE#5 and OLEa#5) did not show transgene expression. All other lines exhibited strong and selective expression in oligodendroglial cells with more than 80% of β-galactosidase positive cells in the CNS corresponding to cells of this lineage (+ and ++). In comparison, less than 20% of β-galactosidase positive cells in the CNS were identified as astrocytes (±) in several lines. Only OLE#2 and OLEa#4 exhibited occasional β-galactosidase labelling of neurons (±). A higher fraction of the oligodendroglial population expressed the transgene in lines OLE#1–3 (++) than in OLEa#1–4 (+). Outside the CNS, weak additional transgene expression was observed for several lines within the DRG, in cartilage or in vasculature as indicated.