Histochemical Studies of Ovary Tissues During the Embryo Sac Development inPaspalum LongifoliumRoxb.

Abstract

SUMMARYIn this study, changes in the distribution of polysaccharides and lipids and stainability of ABB and AB during the embryo sac development in the tetraploid and octoploid of Paspalum longifolium were examined in the glutaraldehyde-fixed, Epon-embedded ovary sections. Starch grains and lipid granules accumulate most abundantly in the ovary wall. They also accumulate in a considerable amount in the embryo sac. The stainability of ABB in different tissue cells are parallel to that of AB except that of the nuclear saps in the nuclei of the embryo sac. Deoxyribonucleic acid in the nuclei of the developing and mature embryo sac, except those of mature antipodals, are hardly stainable with AB and Feulgen reagent. Antipodals may be metabolically very active in transporting nutrients into the embryo sac through the intimate connection between these cells and the nucellus and papillae on the inner surface of antipodal wall adjacent to nucellar cells. They also contain a large amount of starch grains and lipids in liquid state. Both the central cell and egg are higly vacuolated and contain a considerable amount of starch grains and lipid droplets. Filiform apparatus of the two synergids develops from the micropylar wall between these two cells as well as from the micropylar wall adjacent to the region believed to be the degenerated megaspore (s) and is composed mainly of polysaccharides. These polysaccharides seem to have been transformed from starch grains stored in the synergids at an early stage. The cytoplasm around each filiform apparatus stains rather intensely with ABB and AB. Many lipid granules are also present around this apparatus. The nucellar cells below the embryo sac, micropylar integumentary cells, cells in the ovule attachment region (OAR), and cells of the cell strand connecting the OAR and ovary base are all much less vacuolated and rich in cytoplasm. They form a connection from the base of the ovary to the micropylar end of the embryo sac, probably for the translocation of nutrients into the embryo sac. No significant difference in the distribution and concentration of polysaccharides and lipids during embryo sac development in the ovaries of the tetraploid and octoploid was observed, except starch grains and lipid granules, both of which are larger and more numerous in the latter than in the former.