大黍的大小孢子发生、雌雄配子体发育及其淀粉动态

Mega and Microsporogenesis, Development of Female and Male Gametophyte and Starch Dynamics in Panicum maximum

通过石蜡切片，在光学显微镜下系统观察了大黍有性生殖过程中大小孢子发生、雌雄配子体发育及其淀粉动态。大黍花药壁由表皮、药室内壁、中层和绒毡层４层细胞组成。在花药发育过程中，表皮细胞始终积累大、小不等的圆球状内含物，该内含物经ＰＡＳ、苏木精分别染色均呈负反应。表皮细胞外壁在花粉成熟时期略有增厚，且具小刺状突起。绒毡层细胞属腺质型。小孢子母细胞在减数分裂过程中胞质分裂属连续型。成熟花粉粒富含较大颗粒的淀粉。大孢子母细胞减数分裂形成线型四分体，合点端大孢子发育为单核胚囊。４核胚囊进一步发育为４游离核与４细胞共存的８核胚囊。成熟胚囊属蓼型。在胚囊发育过程中，合点珠心细胞中淀粉不明显，在胚囊中合点端淀粉亦少于珠孔端。

Optical studies were made on mega and microsporogenesis,the development of female and male gametophyte and starch dynamics in Panicum maximum through conventional paraffin section.The anther wall consists of epidermis, endothecium, middle layer and tapetum.The globular contents in different size, which have PAS and hematoxylin negative reaction respectively, exist in the epidermal cells during the development of the anther.The outer wall of epidermal cells with spininess becomes slightly thick at mature pollen stage.The meiotic cytokinesis of microspore mother cells conforms to the successive types.The mature pollen is rich in big starch grains.The four linear megaspores are formed by the meiotic division of the megaspore mother cell and the one at the chalazal end develops into uni nucleate embryo sac.The four nucleate embryo sac develops into eight nucleate embryo sac, which is composed of four free nuclei and four cells formed through asynchronous division and cellularization. The mature embryo sac is in accordance with polygonum type.The nucellar cells of the chalazal area have little starch during development of embryo sac. In the embryo sac, the content of starch is greater at the micropylar end than at the chalazal end.Therefore, we suggest that carbohydrates are transported mainly through the nucellar cells of the micropylar area and the surface of embryo sac.