Cover picture: Detail of a myelinating Schwann cell expressing GFP in its cytoplasm. The axon that is sheathed by the Schwann cell is draw in different colors. Note the presence of Schmidt-Lanterman incisures, as repeated bands consisting in two diagonally-oriented lines that cross the cell. An adenovirus expressing GFP was injected in the mouse sciatic nerve in vivo. Three weeks later the nerve was dissected and fixed. The fibers were then teased on a glass slide to allow the observation of infected myelinating Schwann cells that express GFP. For details see the article by Tricaud et al. in this issue (pages 3259–3269).