Fig. 2From: Temporally and spatially controlled death of parenchyma cells is involved in heartwood formation in pith regions of branches of Robinia pseudoacacia var. inermis a A light micrograph of a transverse section of LH-1 sample, stained with safranin, showing the center of a branch of Robinia pseudoacacia L. var. inermis. b Higher-magnification view of pith and xylem. The left side of the latter micrograph corresponds to the outer side of the branch. AP Axial parenchyma cell surrounding vessel elements, P pith, PZ perimedullary zone (with double-headed arrow), RP ray parenchyma cell, V vessel element, Xy xylem. Bars 400 μm in a and 100 μm in b Back to article page