Comparative Studies On Histochemistry Of The Developmental Ovule In Ginkgo Biloba L. And Ginkgo Biloba Var. Epiphylla Mak.

Resin semi-thin section and histochemistry technique were applied on ovule development of Ginkgo biloba L. and Ginkgo biloba var. epiphylla Mak., which made microstructure observation and histochemistry analysis on nutritive materials accumulate characteristic. Then, through high density sampling, we took morphologies, anatomical observation and image recording on ovule development of Ginkgo biloba L. and Ginkgo biloba var. epiphylla Mak.. The main results obtained were as follows:(1) Epiphylla ovule (seed) morphogenesisAt middle to late March, Epiphylla female floral bud took action. In middle April, nearly all leaves expanded. This moment, we can observe the"Gibbosity", which number ranges from 1 to 10, and had the same probability on adaxial and abaxial of the leaf. Late April, the"Gibbosity"grew into ovule shape. In mid-May, epiphylla ovule increased rapidly until to mid-June. By mid-July, epiphylla ovule had the maximum volume. Early August, middle integument of epiphylla ovule completely lignified, and the"conoid"structure totally degenerated. Therefore, there was a cavity at the micropylar end. In mid-August, the outer integument of epiphylla ovule became yellow, while there were still small epiphylla ovule and"Gibbosity". Epiphylla ovule finally developed into epiphylla seed. On the surface of the seed was density white powder. Its volume was smaller than normal seed, and there was no embryo in it.(2) Histochemistry of developmental ovule in Ginkgo biloba L.At early March, there was no tissue differentiation in little ovule of Ginkgo biloba L., and cells of the ovule fell upon starch grains. In mid-March, nucellus tissue and integument occurred in little ovule. Cells in integument had many starch grains, while cells in nucellus tissue without any starch grains. At early April, micropylar and pollen chamber appeared. At the moment, mass starch grains in integument cells, and there were still no nutritive materials in nucellus tissue cells.The development of ginkgo ovule female gametophyte experienced free nuclei stage and cell wall formation stage. At free nuclei stage, the female gametophyte was liquid. We can observe spongy tissue and appendiculate free nucleus through semi-thin section. There were plenty of starch grains in outer integument cells, while in the cells of middle integument,"conoid"structure, tapetum, and flanking parietal tissue there were few starch grains. Female gametophyte formed the cell wall from outer to inner. Female gametophyte appeared gel-like at this stage, and constituted by big parenchyma cells. There were only starch grains in the cells, which were few and little, and distributed by cell wall. At later cell wall formation stage, starch grains in parenchyma cells became more and bigger, while there were still no protein and lipid droplet in them.At the stage of endosperm development, the cells accumulated grains. Then protein occurred. Later, lipid droplet increased. The distribution of nutrients was centre-intensive, sparse-edge. Some ellipse areas in embryo were full of round lipid droplet. In the embryo were many starch grains, which distributed density along cell wall, and were smaller than in endosperm cells; few protein.(3) Histochemistry of developmental epiphylla ovuleThe epiphyllous ovule apparent"gibbosity"at the stage of origin, its main construction was vascular bundle, parenchyma cells, and mucilaginous duct. Mucilaginous duct developed by schizo-lysigenous pattern. Cells around it had few and little starch grains, which were along cell wall. In the center of the"gibbosity", there were a few starch grains, but a lot of starch grains were in the crowed vascular bundle and the junction of"gibbosity"with leaf. No starch grains were found in 1-6 layer cells of the edge of leaves. Obviously black lipid droplet only observed near mucilaginous duct. Abaxial parenchyma cells of"gibbosity"were big and distributed loose, however, cells in junction were small and distributed density.The development of epiphyllous ovule female gametophyte also experienced free nuclei stage and cell wall formation stage. Outer integument and mid-integument had differentiated at free nuclei stage. In mid-integument at micropylar end was a"conoid"structure, which was constituted by big parenchyma cells. No starch grains, protein, lipid droplet in the cells. Cells in outer integument were big and had many starch grains, which along cell wall. There were no starch grains in mid-integument cells. Near Chalazal end, several cells between mid-integument and outer integument exist starch grains. Female gametophyte at early stage of cell wall formation was big parenchyma cells. Nucleus in it was dark, and no starch grains, protein, lipid droplet in it. Then, starch grains occurred, which were small and along cell wall. Later stage of cell wall formation, starch grains became more and bigger. In the vicinity of cell wall, there was black lipid droplet."Conoid"structure at micropylar end became large. No starch grains, protein, lipid droplet in it. Outer integument, mid-integument,"Conoid"structure formed obvious three layers. Mid-integument without starch grains, while at the transition site between mid-integument and out integument had many starch grains.At early stage of endosperm development, the cells accumulated grains. Then, protein occurred among starch grains. The distribution of starch grains and protein were also centre-intensive, sparse-edge. Later, lipid droplet appeared, and between cells turned up more lipid droplet.