INTERACTIONS BETWEEN EMBRYO AND ENDOSPERM DURING EARLY DEVELOPMENTAL STAGES OF MAIZE CARYOPSES (ZEA-MAYS)

The early developmental stages of maize caryopses were studied at a fine structural level. Emphasis was placed on the interactions between the developing embryo and the surrounding endosperm. The placentochalazal region of the endosperm contains cells showing ultrastuctural features of transfer cells, including wall ingrowths. This indicates an important function of these cells in the transport of nutrients supplying the developing embryo. Near the basal region of the embryo, densely cytoplasmic endosperm cells occurred, without wall ingrowths but with a mass of highly ordered rough endoplasmic reticulum, indicating a synthesis function of this part of the endosperm. The products, probably membranes and proteins, are most likely taken up by the suspensor of the embryo. At about 7 days after pollination, endosperm cells degenerate near the embryo axis and the scutellum. The endosperm remnants might then serve as a food supply for the embryo as well.