Glue lines and adhesive penetration into cells, pits and cell walls were examined using fluorescence microscopy. Penetration of epoxy adhesives into cells and intercellular cavities was good and a deeper interface was formed than with phenolic resins. Thus, transversely glued Minoki often showed poor penetration of phenolics into summerwood. Epoxy resin penetrated into vessel pits and walls but often caused separation of glue-filled vessels from the lumen surface, whereas phenolic resin caused little separation. -- AATA