1/2k¯»1/4h, In seed, metabolically active cells of outer layer of the endosperm (in contrast to metabolically inactive cells of most of the endosperm) containing aleurone grains, several hydrolytic enzymes and reserves of phytin (releasing inorganic phosphate and inositol on digestion by phytase). During germination, aleurone cells secrete -amylase into the endosperm, initiating its digestion.