Protein bodies are roughly spherical structures found in seeds, including cereal grains, where storage protein is packed inside a membrane-bound compartment. They are the plant’s way of stockpiling nitrogen and amino acids for the germinating seedling. In wheat, the storage proteins held in these bodies include glutenin and gliadin, the two fractions that together form gluten when flour is mixed with water. The bodies cannot be broken open by mechanical force alone; water makes them swell and rupture, which is exactly what happens during germination and, in the bakery, during dough mixing and fermentation. Their size, number, and protein content vary with variety and growing conditions, and they strongly influence the nutritional value and baking performance of the grain.