Fig. 6

A diagram showing the timing of morphological changes in vacuoles and nuclei and changes in the contents of vacuoles in ray parenchyma cells from the elongation to the death of ray parenchyma cells in Cryptomeria japonica in May, when secondary xylem was actively differentiating. a In the current year’s xylem (the differentiating xylem), ray parenchyma cells contained large central vacuoles and fusiform or elliptical nuclei. b In the sixth annual ring from the cambium (the middle part of the sapwood), ray parenchyma cells contained small protein storage vacuoles (PSVs) and elliptical nuclei. c In the tenth annual ring from the cambium (the middle part of intermediate wood), individual ray parenchyma cells contained PSVs, non-PSVs and deformed vacuoles but still had elliptical nuclei. d In the eleventh annual ring from the cambium (the inner part of the intermediate wood), the numbers of deformed vacuoles were greater than those in the outer part of the intermediate wood. In addition, they contained large vacuoles and elliptical nuclei. e In the middle part of the earlywood of the twelfth annual ring from the cambium (the middle region of the outermost part of the heartwood), ray parenchyma cells contained deformed vacuoles and condensed nuclei exclusively. f Finally, in the inner part of the earlywood of the twelfth annual ring from the cambium (the inner region of the outermost part of the heartwood), ray parenchyma cells contained lipid-like oily droplets and osmiophilic aggregates but no organelles