Abstract: The ultrastructure of the egg and the central cell in Dolichos lablab was investigated. When the embryo sac is mature, cell wall is formed only at the micropylar end of the egg and the synergids. At the chalazal end, no cell wall exists between the egg and the synergid, bet- ween the egg and the central coll, between the synergid and the central cell, and the plasma membranes of the adjacent cells are very close to each other. In some regions between the plasma membrane of the egg and that of the central cell, some moderate electron dense substances are present. Many mitochondria and plastids are present in the egg cytoplasm, but ER and dictyosomes are few. At the micropylar end of the synergid an elaborate filiform appara- tus is distinct, and many ER tubules are dispersed in the cytoplasm of the micropylar end. It shows that the synergid would have a secretory function. The synergid contains numerous rough ER in the cytoplasm at the chalazal end, and between the plasma membrane of the egg and that of the synergid there are some vesiculae, indicating active metabolite transport betwe- en two cells. The central cell displays a high metabolic activity since numerous mitochondria, dictyosomes and ER are present in its cytoplasm. Its cell wall ingrowths form a lot of finger-like projections penetrating into the cytoplasm, which displays the feature of the transfer cell. There are many lipid bodies in the peripheral, cytoplasm. It is suggested that the central cell would play an important role in the nutrition of the embryo sac.

Key words: Embryo sac, Ultrastructure, Dolichos lablab