Fig. 3.

A, The HSV1-TK protein colocalizes with GalC and PLP but not with GFAP. Analyses were conducted by confocal microscopy on 3-week-old brain sections from transgenic mice. Pictures represent single optical sections. TK immunostaining was revealed by Cy3-labeled secondary antibody and GalC and PLP with fluorescein. Small round individual cells immunoreactive for both HSV1-TK and GalC or PLP, portrayed in this figure, were taken in the pons at high magnification. No HSV1-TK-positive cells were stained by the mouse anti-GFAP. Scale bars: top two rows, 10 μm;bottom row, 40 μm. B, MBP mRNA is expressed by proliferating oligodendrocytes. Multiple-labeling of oligodendrocytes was performed on pons sections from a 10-d-old untreated transgenic mouse. MBP mRNA was visualized with a digoxigenin-labeled antisense riboprobe. Dividing cells were identified using a rabbit anti-H3P antibody. Nuclei were stained with DAPI.Arrows indicate dividing oligodendrocytes as shown by the colocalization of the MBP probe and the H3P staining.Arrowheads indicate, in the same field, postmitotic oligodendrocytes showing only MBP staining. Controls were performed using a MBP digoxigenin-labeled sense riboprobe, which did not stain cells in the pons. Scale bar, 10 μm.