埃及白睡莲的胚胎学研究

对埃及白睡莲的大、小孢子的发生,雌、雄配子体的发育,以及胚和胚乳的发育进行了观察研究.结果表明埃及白睡莲的花药壁由5层细胞组成,绒毡层细胞具双核,属于分泌型.小孢子母细胞减数分裂时,胞质分裂属于同时型,小孢子四分体呈四面体型.成熟花粉为三细胞类型,花粉粒表面具有环沟.胚珠为倒生型、双珠被、厚珠心,珠孔仅由内珠被形成.大胞子母细胞减数分裂形成三分体,合点端2个细胞退化,珠孔端1个细胞发育为功能性大胞子.成熟雌配子体由4细胞组成,即2助细胞,1卵细胞和1中央细胞.合子的第一次分裂是横向的,形成的基细胞不再分裂,体积增大后成为一个大的胚柄细胞.而顶细胞进行一系列分裂形成胚.在此基础上,还比较了睡莲目不同属的胚胎学特征.

Embryological Studies in Nymphaea lotus (Nymphaeaceae)

In this paper,we observed the megasporogenesis,microsporogensis,femate and mate ganmetophyte development,embryo and endosperm development in Nymphaea lotus.The anther wall consists of an outer epidermis,an endothecial layer,two middle layers,and a tapetum.The tapetum is secretory and its cells are binuclei.The microspore mother cells undergo simultaneous cytokinesis following the meiotic divisions,which results in the formation of tetrahedral microspore tetrads.The pollen contains three cells when shed,with an encircling latitudinal band-like aperture on their surface.The ovule is anatropous,bitegmic,and crassinucellate,with the micropyle formed only by the inner integument.Meiosis of the megaspore mother cell results in the production of a linner triad of megaspores.The two micropylar megaspore cells degenerate while the chalazal one acts as the functional megaspore.The mature female gametophyte contains four cells(an egg cell,two synergids,and a uninucleate central cell).The first division of zygote is transverse and forms a basal cell and a apical cell.The basal cell does not divide,but increases in size,acting as a unicellular funiculus,while the apical cell divides many times.On the foundation,we also compared the embryological characters of the genera of the Nymphaeales in this paper.