In situ tensile tests parallel to the grain were carried out in an Environmental Scanning Electron
Microscope (ESEM) chamber on Norway spruce (Picea abies [L.] Karst.) samples. The ESEM-mode
combined with a cooling device allowed examination of the specimens at a moisture content
of 12% with unsputtered surfaces. By recording load-displacement curves and observing crack
propagation simultaneously, a detailed image of fracture progress and tissue interaction could be
described. Since these experiments required a sufficient specimen size and geometry, focus was
concentrated on the methodology.