Figure 2.

The microstructure of acid fuchin and calcofluor stained wheat bran (25). Protein appears red, β-glucan in cell walls light blue, and grain coverings (pericarp and intermediate layer) - green/yellow/brown. The importance of this photomicrograph is that wheat bran contains not only the tough outer pericarp and associated diploid maternal tissues, but also a layer of endosperm-related aleurone cells (triploid) which are still alive in the mature grain unlike the apoptosed cells of the starchy endosperm. These live cells supply the necessary biochemical machinery (such as amylase) to mobilize the endosperm for the germinating embryo, and store minerals such as magnesium which will be essential for chlorophyll function. (Used by permission of Per Åman, Professor, Swedish University of Agricultural Sciences).