Cereal Chem 38:374 - 385.  |  VIEW ARTICLE

Protein Granules of Maize Endosperm Cells.

D. N. Duvick. Copyright 1961 by the American Association of Cereal Chemists, Inc. 

Cytoplasmic inclusions composed primarily of protein are found in the maize endosperm. They are roughly spherical, or soap-bubble shaped, numerous, and range in size from near the limit of resolution in the light microscope up to about 3 microns in diameter. They are largest and most numerous in the subaleurone cells, progressively decreasing in size from the outer to the inner cells of the endosperm. Their development, as followed under the light microscope, begins at 15-20 days after pollination in the region under the silk scar and spreads to the other portions of the endosperm. In a given region, enlargement of protein granules starts first in inner cells and then in cells progressively nearer the aleurone. Histochemical tests, plus the positive correlation of period of maximum rate of growth of the protein granules with the reported period of maximum rate of increase in percent of zein during development of the endosperm and the positive correlation of the areas of greatest size of the granules with the reported areas of greatest zein concentration, suggest that protein granules are the major site of zein storage in the maize endosperm.