何首乌胚和胚乳的发育

何首乌为直生胚珠,双珠被。胚发育属于柳叶菜型。心形胚柄最为发达,鱼雷形胚期胚柄奶化。早期胚胎发育营养的主要来源可能是合了中积累的淀粉和胚柄吸收来的营养。成熟胚中积累了大量的蛋白质和淀粉粒。胚乳发育属核型。从球形胚期起,胚乳细胞化过程由珠孔端向合点端逐渐推进。初始垂周壁源于姊妹核间的细胞反或非姊妹核间由次生成膜生的细胞板。初始平周壁源于有丝分裂所产生的细胞板。心形胚期,除合点端保持游离核胚乳吸器外,     

掌叶大黄胚胎学研究

掌叶大黄(Rheum palmatum L.)的花药4室,单或复孢原。药壁发育为单子叶型。腺质绒毡层发育后期出现双核。小孢子四分体为四面体型,胞质分裂为同时型。成熟花粉为3细胞,表面具3条沟。子房1室,单胚珠,直生,两层珠被,由内珠被形成珠孔,厚珠心。单孢原,位于珠心表皮下。直线形或T形大孢子四分体。合点端的大孢子发育为蓼型胚囊。2个极核在受精前合并为次生核。3个反足细胞宿存。胚乳发育为核型,在球形胚末期开始形成细胞。合点端的胚乳核一直不形成细胞,而为游离核的胚乳吸器。在胚乳吸器和其它部位都发现胚乳核融合现象。胚的发育属于紫菀型。胚具小胚柄。成熟胚囊时期出现承珠盘,且存留时间很长,成熟胚期尚存痕迹。     

冠果草的胚胎学研究

冠果草花药壁的发育为单子口十型,绒毡层为周原质团型。小孢子母细胞减数分裂为连续型,四分体呈左右对称式排列,成熟花粉为三细胞型。双珠被,假厚珠心,倒生胚珠。胚囊发育为葱型,成熟胚囊的特点是两个极核分别位于中央细胞两端,不融合成次生核。受精过程中,一个精于与卵核融合形成合子,另一精子先与珠孔端极核融合,之后受精极核再移动到合点端与另一极核融合,形成初生胚乳核。胚的发育为石竹型。成熟胚呈马蹄形,具有2片真叶。胚乳发育为沼生目型。随着胚的发育,胚乳细胞逐渐解体,成熟种子中无胚乳。     

荞麦胚和胚乳的发育及贮藏营养物质的积累

荞麦原胚期,胚乳为游离核期。球形胚晚期,胚乳开始细胞化。心形胚期,胚囊中部形成一层“开放细胞”。鱼雷形胚期,胚囊中部有５－７层胚乳细胞。子叶弯曲胚期,胚乳全部形成胚乳细胞,具传递细胞特征的合点胚乳吸器形成。胚乳细胞的初始垂周壁来自于自由生长壁和胞质分裂形成的细胞板;初始平周壁由自由生长垂周壁分友相接形成,及有丝分裂的细胞板形成。开花后９ｄ,胚乳细胞积累淀粉,比胚细胞积累早６ｄ。开花后１５ｄ,胚乳最     

刺梨胚及胚乳的发育

本研究对单瓣刺梨胚及胚乳的发育过程进行了观察,获得如下主要结果:1.刺梨胚的发育属于紫菀型的一种变异类型。原胚发育早期,在胚体顶端具有明显的胚芽原细胞。成熟胚为典型的双子叶植物胚的形态,在子叶中贮藏大量的蛋白质粒。2.刺梨的胚乳属核型。经游离核时期以后形成胚乳细胞。紧邻胚囊周界壁的表层胚乳细胞可以进行平周分裂,产生层叠状的胚乳周缘层。此种后形成的胚乳,我们称之为次生胚乳。当次生胚乳形成时,其余的胚乳细胞逐渐解体,最后几乎完全消失。次生胚乳只在合点处解体,其余保留至种子成熟。3.发现了开花后一些胚珠中无胚或胚和胚乳在发育早期退化的现象,可认为是刺梨种子不育的一个重要原因。     

丫蕊花的双受精及胚和胚乳发育的初步观察

丫蕊花（Ypsilandra thibetica Franch.)为珠孔受精,进入胚囊的两个精子分别与卵细胞和中央细胞进行正常的双受精,其受精作用属有丝分裂前型,受精后的初生胚乳核立即分裂,其发育方式为沼生目型,到发育后期,由游离状态的胚乳核形成胚乳细胞时,珠孔室和合点室都形成胚乳细胞,合子的休眠期很长,而且胚的发育过程较为缓慢,种子成熟时胚尚无器盲的分化,本文还观察了以上发育过程中淀粉粒,蛋白质的动态。     

柽柳胚和胚乳发育的观察

利用常规石蜡制片技术,对柽柳（Tamarix chinensis Lour.）胚和胚乳的发育过程进行了观察。结果表明,胚发育属茄型,其基细胞先行纵裂。胚柄基部发育迅速,具吸器作用,球形胚期胚柄最为发达,其细胞质丰富,贮藏淀粉类物质,至晚心形胚期胚柄依然存在。助细胞被受精产生多胚现象。胚乳发育属核型,初生胚乳核常常晚于合子分裂,胚乳核的分裂速度慢于胚体细胞的分裂速度。当胚乳游离核为 32个时,以自由生长细胞壁的方式进行胚乳细胞化。胚乳细胞进一步增殖极少。珠心细胞只有两层,细胞核大,胞质丰富,内含贮藏物质,至心形胚期逐渐解体。     

丫蕊花的双受精及胚和胚乳发育的初步观察

丫蕊花（Ypsilandra thibetica Franch.)为珠孔受精,进入胚囊的两个精子分别与卵细胞和中央细胞进行正常的双受精,其受精作用属有丝分裂前型,受精后的初生胚乳核立即分裂,其发育方式为沼生目型,到发育后期,由游离状态的胚乳核形成胚乳细胞时,珠孔室和合点室都形成胚乳细胞,合子的休眠期很长,而且胚的发育过程较为缓慢,种子成熟时胚尚无器盲的分化,本文还观察了以上发育过程中淀粉粒,蛋白质的动态。     

篦子三尖杉的胚胎学研究及其系统位置的探讨

篦子三尖杉Cephalotaxus oliveri的成熟花粉包含两个细胞,花粉管在精原细胞产生后 经历了一年的休眠期; 精原细胞分裂产生两个体积不等的精子; 雌配子体游离核经12次分裂后形成细胞壁; 窄长的颈卵器单个顶生; 卵细胞中含有大量类核仁状体; 受精时,雌雄核在分裂中期完全融合; 原胚游离核在16核时产生细胞壁; 原胚具冠细胞; 无裂生多胚现象; 成熟胚 二枚子叶。总之,蓖子三尖杉与本属其它种相比,存在明显的差异。如精原细胞分裂前细胞中心细 胞质浓缩成星状放射区域; 苗端早在胚成熟前分化形成明显的突起,以及成熟胚的子叶极为发达等等。因此,作者赞同将蓖子三尖杉在本属中另立一组的观点。     

桔梗胚乳吸器的细胞化学研究

对桔梗的胚乳吸器进行了细胞化学研究,结果显示,胚乳吸器的细胞质、胚乳吸器周围解体的珠心细胞和珠被细胞均呈强ＰＡＳ正反应。随着胚乳吸器的发育,吸器附近的珠心细胞和珠被细胞中贮存的大量淀粉粒逐渐减少和消失。胚乳吸器的细胞质,尤其是与胚乳本体细胞交界处的细胞质富含蛋白质。在球形胚前期,胚乳细胞中已积累大量的蛋白质颗粒。结果表明胚乳吸器起营养物质的吸收和转运作用,向胚乳提供养料。     

Fertilization and Histochemical Investigation on Pulsatilla chinensis (Bung) Regel

Fertilization and variation of protein and starch grains in Pulsatilla chinensis (Bung) Regel have been studied at light microscopic level with histochemical test. Based upon the observations, the main conclusions are summarized as follows: The mature pollen grains are two-celled in which the generative cell shows the stronger protein staining than the vegetative cell. And vegetative cells are full of starch garins. When the pollen tube enters into the embryo sac, one synergid is destroyed, or in a few cases synergids are intact. Occasionally two synergids are disorganized as pollen tube penetrates. However, most of the remaining syuergids break down during fertilization, only in a few cases it remains till early stage of embryo development. The contents discharged by the pollen tube consist of two sperms, which stain intensely blue with protein dyes, a great amount of protein and starch grains. Mature female gametophyte (embryo sac) consists of an egg apparatus, central cell, which has a huge secondary nucleus, and antipodal apparatus which retain in course of fertilization. A few of embryo sac contain two sets of egg apparatus, a central cell with two huge secondary nuclei and two sets of antipodal apparatus. In some nucleoli of the central cell the comb-like structure pattern may be detected clearly. There are 1–2 small nucleoli in some egg cells and central cells. All the cells in embryo sac show protein positive reaction. According to the different shades of the color in cells, its may be arranged in the following order: antipodal cells, synergids, central cell and egg cell. Only a few small starch grains are present near nuclei of central cell and egg cell before fertilization, but no starch grains remain in most of the central cell, the synergids and antipodal cells. The fertilization is of the premitotic type. The fusion of the sexual nuclei progresses in the following order: 1, sperms approach and lie on the egg nucleus and secondary nucleus; 2, sperm chromatin sinks themselves into female nucleus, and male nucleolus emerges with the sperm chromosome; and 3, male nucleoli fuse with the nucleoli of egg nucleus and central cell nucleus, and finally forming the zygote and the primary endosperm cells respectively. Nevertheless, as it is well known, the fertilization completes in central cell obviously earlier than that in egg cell. Though it has been explained in cereals and cotton, in Pulsatilla chinensis the main reason is that nucleolar fusion of the male and female nucleoli in egg nucleus is slower than that in secondary nucleus. And the dormancy of the primary endosperm nucleus is shorter than that of the zygote. In the process of fertilization, histochemical changes are considerably obvious in the following three parts: 1, from the begining of fusion of male and female nuclei to form zygote and primary endosperm cell, Protein staining around female nucleus appears to increase gradually; 2, no starch grains are detected in embryo sac. Though only starch grains are carried in by pollen tube, they are completely exhausted during this period; and 3, near completion of fertilization starch grains appear again in zygote, however, not yet in primary endosperm nucleus till its dividing for the first time. The present study reveals that antipodal cells and synergids seem to play a significant role in nutrition of the embryo sac during the fertilization.     

竹节参雌配子体发育的研究

本文报道了竹节参(Panax japonicus C.A.Mey)雌配子体(胚囊)的发育过程。竹节参大孢子母细胞减数分裂产生线形排列的大孢子四分体。胚囊发育属蓼型,由合点端大孢子发育而成。游离核胚囊时期,胚囊珠孔端的细胞器种类和数量都较胚囊合点端多;胚囊合点端相邻的珠被细胞中有含淀粉粒的小质体,与胚囊珠孔端相邻的退化中的非功能大孢子中则有含淀粉粒的大质体和大类脂体。成熟胚囊中,反足细胞较早退化;极核融合成次生核;卵细胞高度液泡化,细胞器数量较少;助细胞则有丰富的细胞器和发达的丝状器。PAS反应表明,受精前的成熟胚囊中积累淀粉粒。次生核受精后,很快分裂产生胚乳游离核,到几十至数百个核时形成胚乳细胞。卵细胞受精后则要经过较长的休眠期。     

Fertilization and Embryo Development of Populus lasiocarpa Oliv

The double fertilization and embryo development of P. lasiocarpa were studied using cytochemical method for DNA, RNA, polysaccharides and proteins. Stigmas were covered by secretion stained positively with PAS and mercuric bromphenol blue at receptive stage. The pollen grains germinated on the stigma in large quantities 6 hours after pollination. Fertilization started at the 6th days after pollination. The sperm nucleus fused with the secondary nucleus faster than the sperm nucleus with the egg nucleus. The syngamy belonged to peremitotic type. A great deal of starch grains in the embryo sac disappeared during fertilization. The endosperm was nuclear type and becomed a cel 31 days after pollination. The endosperm was characterized by a dense cytoplasm rich in protein. No discrete starch grains were observed in endosperm. Afterwards, the endosperm was consumed by the developing embryo, thus the mature seeds were non-endospermous. The zygote was dormant for 6–8 days. During the dormency, many striking changes took place, and then, the zygotes showed more pronounced polarity. These changes included the shinkage of the large vacuole, the reduced size, the reappearance of large vacuole, the enlarging of the size. The embryogenesis conformed to the Solanad type. The ovules matured into seeds successively 44 days after pollination. The mature embryo was straight. Two cotyledons folded each other.     

Accumulation of Metabolites during Seed Development in Trifolium repens L.

Metabolite deposition during seed development was examined histochemicallyin Trifolium repens by light- and fluorescence microscopy. Allendosperm haustorium at the chalazal pole of the embryo sacand wall protrusions in cell walls of the suspensor and theembryo sac suggest that transfer of metabolites from maternalto offspring tissue takes place primarily at these sites. Thisis further supported by prominent cutinization of the interpolarregion of the embryo sac wall, accumulation of starch in integumentaltissue at the embryo sac poles, and breakdown of interpolarendothelial cells. Decomposition of osteosclereid starch isfollowed by accumulation in the cellular endosperm and subsequentlyin the embryo parallel to endosperm degradation. The starchaccumulates gradually inward from the subepidermal cells ofthe embryo to the stele. Protein bodies are formed in the vacuolesalong the tonoplast, later to be cut off in vesicles releasedinto the cytoplasm. At maturity the embryo is packed with proteinand starch, but without lipid reserves. Phytin is observed inthe protein bodies. The mature embryo is surrounded by a proteinand starch containing aleurone layer which originates from theendosperm.Copyright 1994, 1999 Academic Press White clover, protein, starch, cuticle, embryo sac wall     

Ovule,Female and Male Gametophyte and Fertilization of Kingdonia uniflora Balfour F. et W. W. Smith

The structure of ovule, female and male gametophyte, double fertilization and the distrubution of starch grains during the fertilization have been studied. The main results are as follows: ( 1 ) Ovule The ovule is anatropous, unitegmic and tenuinucellate. The nucetlus appears cylindric, since megaspores and embryo sac development, its internal cells of nucellus become disorganized, so that only a single layer of epidermal cells remains toward the side of the micropyle, On the other hand, the integument is not as long as nucellus, as a result micropyle is not formed. And no vascular bundle is found in the integument. (2) Female gametophyte The mature embryo sac is slender and is composed of an egg cell, two synergids, a central cell and three antipodal cells. The egg cell is situated slightly away from the tip of embryo sac. Some of them contain starch grains. Synergids occupy the tip of embryo sac. Its wall at micropylar region appears irregular in thickenes and irregular in ingrowths to form the filiform apparatus. The centrateell is very large, and strongly vacuolated Two polar nuclei come to contact closely with each other, but not fuse, or to fuse into a large secondary nucleus before fertilization. The polar nuclei or the secondary nucleus are usually situated at the middle-lower position of the central cell or nearer to the chalazal end above the antipodal cell. It is different from egg cell, no starch grains are found here. In most embryo sacs three antipodal cells are found. They are not as large as those in other plants of Ranunculaceae. But six antipodal cells or the antipodal cell with two nuclei may rarely be found. Like synergid, the wall of them appears not only irregularly thickened, but clearly with irregular ingrowths. In a few antipodal cells the starch garins are usually found near the nucleus. By the end of fertilization, antipodal cells become disintegrated. (3) Male gametophyte Most pollen grains are two-celled when shedding, and rich in starch grains. A few of them contain single nucleus or three-celled. (4) The double fertilization The fertilization of Kingdonia unifiora Balfour f. et W, W. Smith is wholly similar to some plants of Ranunculaceae studied. First, the pollen tube penetrates a degenerating synergid. And the pollen tube discharges its contents with two sperm nuclei into the degenerating synergid cell. One of the two sperms fuses with the nucleus of the egg, and the other fuses with two polar nuclei or the secondary nucleus of the central cell. If one sperm nucleus at first fuses with one of the polar nuclei, and then the fertilized polar nuclei again fuses with other polar nucleus. Secondly, the fertilization of the polar nuclei or the secondary nuclei completes earlier than that of the egg. The primary endosperm nucleus begins to divide earlier than the zygote. It seems that one of the sperm nuclei come to contact with egg nucleus, the other has already fused with polar nuclei or the secondary nucleus. The zygote with a single nucleolus appears until the endosperm with 16–20 cell. Thirdly, before and after fertilization there are one to some small nucleoli in egg nucleus and polar nuclei or secondary nucleus. However they increase in quantity from the beginning of the fusion of male nucleis. These nucleoli quite differ from male nucleoli by their small size, and most of them disappear at the end of fertilization. It may be concluded that the small nucleoli increase in quantity is related to the fusion of male and female nuclei. In the duration of fertilization, in ovule starch distribution is in the basal region of integument. But in embryo sac, onlysome egg cells, or zygotes contain starch grains, a part of which was brought in by pollen tube. Sometimes the starch grains are found in some synergids and antipodal cells. No starch grains are found in the central cell.     

Embryological Studies of Codonopsis pilosula Nannf.

This paper reports the studies of megasporogenesis and microsporogenesis, development of female and male gametophytes, fertilization, and development of embryo and endosperm, The anther wall consists of four layers, i.e. epidermis, endothecium, middle layer and tapetum. Part of the tapetum cells originates from the primary parietal cells, and the other part comes from the basic tissue of the anther partition. Tapeta? cells are uninucleate or binucleate, and belong to the secretory type. Microsporocyte originates directly from the primary sporogenous cell, Cytokinesis is of the simultaneous type. Arrangement of microspores in tetrad is isobilateral. Mature pollen grain is of the 2-celled type. The ovary is tricarpellum, trilocular with many ovules. The ovule is mono-integinous, tenui-nucellar and anatropous. The embryo sac originates from the single-archesporial cell. The one chalazal megaspore in linear tetrad is the functional megaspore. The development of embryo sac is of the Polygonum type. Before fertilization, two polar nuclei fuse in to a secondary nucleus and the antipodal cells degenerate. Fertilization is porogamy, fusion of one sperm with secondary nucleus is faster than that of one sperm with egg nucleus. The development of endosperm is of the cellular type. The first three divisions of endosperm ceils are regular. Two endosperm cells near the ends of chalaza and the micropyle develop into haustorium without division. The haustoria gradually degenerate at the late stage of globular embryo. The mature seeds contain abundant endosperm. The development of embryo is of the Solanad type. The suspensor consists of 12–20 cells. The optimum development of the suspensor is at the early stage of the globular embryo. It begins to degenerate after late globular stage. The embryo develops from proembryo, heartshaped embryo, dicotyledenous- to mature embryo.     

A CYTOCHEMICAL STUDY OF EMBRYO SAC DEVELOPMENT IN STELLARIA MEDIA

Megasporogenesis and embryo sac development in Stellaria media were investigated using cytochemical methods for the demonstration of nucleic acids, proteins, and polysaccharides. RNA concentrations were high in the archesporial cells, low in the megaspore mother cell, and increased again to high concentrations with the formation of the megaspore and 2-, 4-, and early 8-nucleate embryo sac. RNA levels were also high in the egg and primary endosperm nucleus but low in the synergid and antipodal cells. Nucleolar size and vacuolation were indicative of RNA synthetic activity. Protein concentrations were parallel in concentration and distribution to those observed for RNA. Polysaccharides were conspicuously absent from all stages except the synergids and nucellar cells. Feulgen-stained DNA was demonstrable in the antipodal cells, megaspore mother cell, and megaspore cell, but was not visible in the 2-, 4-, or early 8-nucleate embryo sac. Feulgen staining was also absent from the egg and primary endosperm nucleus but was visible in the synergids and antipodals. Histones were difficult to visualize anywhere except in the egg cytoplasm and the nuclei of the antipodals.     

Embryological Studies on Sagittaria guayanensis H. B. K. Subsp. lappula (D. Don) Bojin (Alismataceae)

This paper deals with the embryological characteristics of Sagittaria guayanensis H. B.K. subsp. lappula (D. Don) Bojin. The anther wall development follows the Monocotyledonous type. The cytokinesis of microspore mother cell in meiosis is of the Successive type. The tetrads of microspores show an isobilateral arrangement, and the mature pollen grains are 3-celled. The ovule is bitegminous, pseudo-crassinucellate and anatropous. The megaspore mother cell originates directly from a single archesporial cell. The mature embryo sac consists of 7 cells including 8 nuclei and conforms to the Allium type. The two polar nuclei do not fuse into a secondary nucleus before fertilization. Instead, one sperm fuses with the micropylar end polar nucleus first , and the fertilized polar nucleus then migrates to the chalazal end, where it fuses with the second polar nucleus, forming the primary endosperm nucleus. The embryo development conforms to the Caryophyllad type. The mature embryo is U-shaped and forms the embryonic shoot apex accompanied by two leaves. The endosperm development corresponds to the Helobial type. The primary endosperm nucleus (invariably lying in the chalazal part of the embryo sac) divides and forms two chambers:large micropylar one and small chalazal one. The chalazal endosperm chamber remains binucleate, while, in the micropylar chamber free nuclear divisions occur and then cellnlarization takes place. During the embryo formation the endosperm gradually degrades and can not be found in the mature seed. The subgenus Lophotocarpus is different from the subgenus Sagittaria in some embryological aspects, especially in the structure of mature embryo sac and the double fertilization process.     

Studies of Ultrastructure and ATPase Localization of Mature Embryo Sac in Vicia faba L.

Studies of ultrastructure and ATPase localization of the mature embryo sac in Vicia faba L. show that the egg cell has no cell wall at thechalazal end, it has a chalazally located nucleus and a large micropylar vacuole. There are many nuclear pores in the nuclear membrane. The cytoplasm is restricted around the nucleus. Dictyosome and mitochondria are few. There are some starch grains and lipid grains in the egg cytoplasm. There are no obvious differences between two synergids. No cell wall is seen at the chalazal end either, but there are some vesicles which project to vacuole of the central cell and fuse with its vacuolar membrane. Plasmodesmata connections occur within the synergid wall where it is adjacent to the central cell. The synergid has a micropylarly located nucleus and a chalazal vacuole, the nucleus is irregularly shaped. The synergid cytoplasm is rich in organelles. The filiform aparatus is of relatively heterogeneous structure. The central cell is occupied by a large vacuole and its cytoplasm is confined to a thin layer along the empryo sac wall, but is rich in various organelles, starch grains and lipid bodies. Nucleolar vacuoles are often present two polar nuclei. The nuclear membranes of two polar nuclei have partly fused. ATPase reactive product was located obviously at the endoplasmic reticulum in cytoplasm of the egg cell and central cell. The embryo sac wall consists of different density of osmiophilic layer. There are some wall ingrowths in chalazal region of the embryo sac. The long-shaped and cuneate cells of chalazal region are peculiar. Special tracks of ATPase reactive products are visible at their intercellular space which may be related to transportation of nutrients.