InLagerstroemia speciosa, the decrease in size of the egg and its micropylar vacuole immediately after fertilization is followed by a progressive and marked expansion of the cell. Thepas-positive cell wall material in egg is confined to the micropylar half. Soon after fertilization, but before completion of decrease in size of the zygote, its cell wall grows in thickness. A complete wall is not formed around the zygote. The bulk of the insoluble polysaccharides in the cytoplasm is localized at the chalazal pole of the egg and zygote. Following fertilization, the size and number of starch granules in the egg cytoplasm significantly increased followed by a decrease and again an increase during zygote development. The morphological changes in the egg following fertilization are probably related to the osmolarity of the cell and of the vacuole which would account for the change in cell size.