矮沙冬青雌配子体及胚胎发育研究

矮沙冬青子房单心皮1室,边缘胎座,弯生胚珠,胚珠具双珠被、厚珠心。大孢子孢原细胞发生于珠心表皮下,大孢子母细胞减数分裂形成直线排列的四分体,合点端大孢子具功能,并按蓼型胚囊发育,雌配子体成熟于4月中旬。双受精后,胚乳发育为核型。在矮沙冬青大孢子发生、雌配子体和胚胎发育过程中未发现异常现象,因此认为矮沙冬青濒危不存在雌性生殖结构与发育过程异常的内在因素。     

The Nucellus, Embryo Sac, Endosperm, and Embryo of Aesculus and their Interdependence during Growth

Immature fruits of Aesculus yield powerful stimuli to growthand cell division. Therefore, the developing fruit of Aesculuswoerlitzensis Koehne has been investigated from pollinationto maturity. The fluid, or liquid endosperm, which containsthe growth-promoting substances is produced in a large vesiclewhich forms at the chalazal tip of the embryo sac. As the vesiclegrows, it encroaches upon the nucellus and, when the embryodevelops, one of its cotyledons penetrates into the vesicleof the embryo sac where it grows and absorbs the contents. Theembryo, which has only a vestigial suspensor, reaches the vesicleby growing along the neck of the long curved embryo sac. Thecotyledon which first penetrates the vesicle grows into a massivestructure; the other remains small. The tip of the cotyledonseems to function as an absorbing surface, for the endospermwith which it comes into contact disorganizes. Fertilizationand the presence of a viable embryo at the micropylar end ofthe embryo sac therefore sets in train a number of other events.These are the extensive development of the nucellus at the chalazalend of the embryo sac, the swelling of the vesicle and the formationof a free nuclear and some cellular endosperm, and the disorganizationof the nucellus as it is encroached upon by the vesiculate embryosac. Attention is directed to the organization of the nucellusin the vicinity of the embryo sac. Files or richly protoplasmicnucellar cells(hypostase) which converge upon the chalazal tipof the embryo sac suggest a principal route by which the vesiclemay be nourished. Special attention is drawn to the very differentsizes of cells, their nuclei and nucleoli, in the differentparts of the nucellus. The growth and development of the embryohas also been traced from the zygote to the mature seed. Thenutritive role of the veaiculate embryo sac, and the supplyof growthstimulating substances, through the function of a cotyledonas an absorbing organ, are now seen as important features ofthe development of the Aesulus embryo in the ovule. Many outstandingproblems still remain. The sequential events that follow fertilizationin the different interdependent regions (nucellus, embryo sac,cotyledon, &c.) are here described, but not casually explained.     

七筋姑的大小孢子发生雌雄配子体发育及多糖物质的动态

七筋姑(Clintonia udensis Trautv. et Mey)具倒生胚珠、双珠被、薄珠心、单个孢原。大孢子母细胞减数分裂后形成1 3排列,合点端三核退化,珠孔端有功能的大孢子核进行两次有丝分裂。成熟胚囊具5核或6核,即1组卵器、1上极核、合点端的1个或2个退化核。胚囊发育为四孢子、高度退化的贝母型。花药壁由表皮、药室内壁、两层中间层及绒毡层组成,发育属单子叶型。绒毡层解体方式为分泌型。小孢子母细胞减数分裂时胞质分裂为连续型。二轴对称式四分体,2-细胞成熟花粉粒。组织化学表明:大小孢子发生及雌雄配子体形成过程中的不溶性多糖颗粒的分布呈现规律性变化。     

EMBRYO SAC LACKING ANTIPODAL CELLS IN ARABIDOPSIS THALIANA (BRASSICACEAE)

Ultrastructure of the embryo sac lacking antipodals in prefertilization stages in Arabidopsis thaliana has been examined 2 hr before and 5 hr after manual cross pollination. The cytoplasm of both synergids before fertilization is rich in ribosomes, mitochondria, and rough endoplasmic reticulum, and also contains several microbodies and spherosomes. The filiform apparatus includes electron-dense material and a fibrous part. Many cortical microtubules appear in the filiform apparatus area. One of the two synergids degenerates before fertilization. The synergids, the egg cell, and central cell have a rich cytoskeleton of microtubules; only the synergids appear to contain microfilaments. At the chalazal end, the antipodals are initially present but degenerate by the time of pollination in most embryo sacs in the starchless line studied. The embryo sac is completely surrounded by a wall containing an electron-dense layer, separating it from the nucellus, including the chalazal end. When the antipodals have degenerated, the electron-dense layer disappears at the chalazal end only, and the wall between the central cell and the nucellus is homogeneous. Between the central cell and nucellar cells no plasmodesmata are found. The membranes of both antipodal cells at the chalazal end of the embryo sac appear sinuous, like those of transfer cells. The central cell has plastids preferentially distributed around the nucleus, but the other organelles are randomly distributed. The central cell in the embryo sac and the adjacent chalazal nucellar cells show a transfer-cell function in the embryo sac after the antipodals degenerate.     

水蔗草兼性无融合生殖胚胎学研究

对水蔗草 (ApludamuticaL .)的生殖方式进行研究 ,结果表明水蔗草进行兼性无融合生殖。胚囊发育分为两种类型 ,即有性生殖的蓼型和无孢子生殖的大黍型。无融合生殖胚囊频率为 6 0 .74%。在大孢子母细胞发育至四分体后 ,珠孔端的 3个大孢子解体。合点端的大孢子未解体时 ,邻近大孢子的 1个珠心细胞开始特化 ,形成无融合生殖的原始细胞 ,由该原始细胞发育形成有 1个卵细胞、1个助细胞和 2个极核的四核胚囊。     

水蔗草兼性无融合生殖胚胎学研究

对水蔗草(Apluda mutica L.)的生殖方式进行研究,结果表明水蔗草进行兼性无融合生殖.胚囊发育分为两种类型,即有性生殖的蓼型和无孢子生殖的大黍型.无融合生殖胚囊频率为60.74%.在大孢子母细胞发育至四分体后,珠孔端的3个大孢子解体.合点端的大孢子未解体时,邻近大孢子的1个珠心细胞开始特化,形成无融合生殖的原始细胞,由该原始细胞发育形成有1个卵细胞、1个助细胞和2个极核的四核胚囊.     

小盐芥大孢子发生和雌配子体发育

本论文研究了小盐芥(Thellungiella halophila)大孢子发生和雌配子体发育过程及该阶段与花蕾、花、果实外部形态的相关性。结果如下: 小盐芥雌蕊由2心皮组成, 侧膜胎座, 每室胚珠多数, 弯生, 双珠被, 薄珠心。孢原细胞位于珠心表皮之下, 直接起大孢子母细胞的功能。大孢子四分体线形排列, 合点端大孢子为功能大孢子, 胚囊发育为蓼型。     

小盐芥大孢子发生和雌配子体发育

本论文研究了小盐芥（Thellungiella halophila）大孢子发生和雌配子体发育过程及该阶段与花蕾、花、果实外部形态的相关性。结果如下：小盐芥雌蕊由2心皮组成,侧膜胎座,每室胚珠多数,弯生,双珠被,薄珠心。孢原细胞位于珠心表皮之下,直接起大孢子母细胞的功能。大孢子四分体线形排列,合点端大孢子为功能大孢子,胚囊发育为蓼型。     

星星草大、小孢子发生与雌、雄配子体发育的观察

利用常规石蜡制片法研究了星星草[Puccinellia tenutiflora(Griseb．)Scribn．et Merr．]大、小孢子发生及其雌、雄配子体的发育过程。主要结论是：(1)小孢子母细胞减数分裂过程中的胞质分裂为连续型,四分孢子为左右对称型;(2)成熟的花粉为三细胞型,具单萌发孔;(3)花药壁由4层结构组成,最外层为表皮,其内分别为药室内壁、中层、绒毡层,绒毡层为分泌型,花药壁的发育属于单子叶型;(4)星星草为单子房,单胚珠,双珠被,薄珠心,倒生型胚珠。大孢子母细胞经减数分裂形成线形排列的4个大孢子,合点端大孢子具功能;(5)胚囊发育属于蓼型,成熟胚囊形成时,反足细胞经无丝分裂形成4～6个反足细胞,反足细胞内可能存在多次DNA复制过程。