3) Deposits of phytin in the form of globoids are located in protein bodies in some but not all the cells of endosperm and embryo tissues. Phytin is found only in tissues that remain alive during desiccation, e.g. in cereals it is present in the protein bodies of aleurone layer cells but not in the protein bodies of starchy endosperm cells. Small electron-dense particles, thought to be phytin, are visible in vacuoles in transmission electron micrographs of the peripheral layers of barley endosperm before differentiation of the aleurone layer takes place. They increase in size only towards the end of the grain- filling period, when vacuoles in the cells of the aleurone layer are being filled with protein.