黑节草双受精过程及胚胎发育的研究

黑节草从传粉到受精约需１３０ｄ,精子在花粉管中形成,胚囊发育属蓼型胚囊,因反足细胞较早退化,故受精前胚囊多只由卵器和中央细胞组成。精卵核融合时,精核染色质进入卵核后凝集成颗粒状,并在原位与卵核的染色质融合,雌、雄性核仁一直维持至合子的第一次分裂期前。双受精作用正常,属于有丝分裂前配子融合类型,初生胚乳核发生２－３次分裂后逐渐退化消失,胚的发育局限于球形胚阶段。     

水稻(Oryza sativa L.)的受精作用

本文对四个水稻品种的双受精过程作了细胞形态学的观察。作者看到,水稻在受精过程中常常有多条花粉管相继伸向珠孔,并把花粉管内含物注入胚囊。注入胚囊的内含物进入两助细胞之一,在卵细胞的一侧形成钩状构造。当合子发育成原胚时,钩状构造就逐渐消失。卵细胞与极核,除了通常的单精受精以外,有少数可能是属于多精受精的现象。卵细胞多精受精时,超数精子不但进入细胞质,而且进入细胞核。精子还可能进入原胚的胚胎细胞。     

大麦未授粉子房培养的胚胎学观察

在离体条件下诱导了大麦未授粉子房内的胚状体发生。雌核发育的胚主要起源于卵器,也可能起源于反足器。原胚发育与胚分化过程中既有类似体内合子胚的正常类型,也有变态的类型。未受精的极核亦可分裂成类似胚乳的游离核。研究了胚囊发育时期与培养方式对诱导胚胎发生的影响。     

植物的受精作用 第三讲 雄性配子与雌性配子融合的过程

当花粉管进入胚囊后,立即释放出其中的内容物,包括两个精子。接着发生雌雄配子的融合:一个精子与卵融合,形成合子,进一步发育成胚;另一个精子与中央细胞的极核(通常两个)融合,形成初生胚乳核,发育成为胚乳。受精作用发生的两种融合的现象,称为双受精。这是被子植物独具的特点。     

唇鲳精子早期入卵观察

用扫描电镜对唇鳃成熟卵子及早期精子人卵过程进行观察。结果显示,唇鲋成熟卵子在动物极中央有一深凹陷的表面光滑的精孔器,其外径2．512μm,内径2．330μm,精子直径1．567μm。混匀的精卵刚遇水时,没有精子进入精孔器。受精后1s,精孔器内出现精子。受精后5S,组织切片显示,精子已经进入卵子内,并形成具有强烈抑制多精人卵作用的受精锥。受精后10S,精子在精孔器前庭集结,尚未形成受精塞。受精后20S,在精孔器内形成受精塞。受精塞没有阻塞精孔管,经分析它不是来源于皮层反应产物。受精塞形成后,可以吸附人卵的精子,这对多精入卵有积极的抑制作用;精子尾部在入卵过程中相互缠绕,这也是减少多精入卵的重要机制。受精后30s,受精塞和吸附的精子向精孔器外移动。受精后50S,受精塞和吸附的精子堵塞精孔器。受精后60s,受精塞吸附的精子开始解体,但是由于精孔管未封闭,还有精子通过精孔管进入到质膜。在人工受精过程中,卵子的单精受精屏障会因其周围精子密度大、精子与卵子距离短、精子运动速度快而被打破,从而导致这些卵子出现多精入卵的现象。受精后80s,精孔管仍然没有封闭,精孔器附近的精子明显出现活动能力的差异：精孔器外面的精子活动能力最强,精孔管旁边的精子活动能力较弱;精孔管外堆积的精子活性消失,受精塞吸附的精子已开始解体,经初步分析,这可能是进入其内的精子耗能有所差异的结果。受精后100S,受精塞吸附的精子解体。     

水稻中央细胞发育期间超微结构变化的观察

本文通过透射电镜对水稻受精前胚囊中央细胞发育过程中超微结构的变化进行观察。结果表明,八核胚囊形成后很快就进行细胞化形成7个细胞,其中刚形成的中央细胞由1个大液泡、2个极核（珠孔端和合点端各1个）和一些含有丰富细胞器的胞质组成。中央细胞以后的发育主要是极核的发育和极核周围胞质的变化。极核发育经历以下过程：a．2个核都膨大呈“椭圆”形。核周围胞质呈不对称分布。b．2个核分别向胚囊中央移动并相互靠近。之后2个极核调整排列方式,由纵排（即与胚囊纵轴平行）变成横排。此时期有细胞质“桥”联结珠孔端卵器、2个极核和合点端反足细胞器。c．横排的极核移向卵器,并排列于卵细胞之上。此时胚囊未明显膨大,但极核相靠近的两边核膜有许多处已形成“融合桥”,核周围的胞质也起较大的变化,如质体内淀粉消失和光面内质网增加等。极核进一步发育直至胚囊成熟期间,极核排列方式及其周围胞质组成未观察到明显的变化,但胚囊体积明显增大。     

裸子植物种子的胚乳由何而来?

答:裸子植物胚珠里的胚囊内有许多个颈卵器生长于配子体组织中,每个颈卵器中有一个大型的卵细胞,没有极核细胞,卵受精后发育成胚(其中有一个发育成熟,其余的败育).胚乳是由雌配子体——成熟的胚囊发育而来的。这种现象有别于被子植物双受精后形成的胚     

大叶杨配囊及胚珠的形成和发育

本文应用细胞化学方法研究了大叶杨胚珠、胚囊的形成和发育过程中核酸、蛋白质及不溶性多糖的分布和消长。大孢子母细胞、大孢子四分体及功能大孢子中含较少不溶性多糖,但却含丰富的RNA和蛋白质。功能大孢子经分裂发育成八核的蓼型胚囊。四核胚囊开始积累细胞质多糖,成熟胚囊中除反足细胞外充满淀粉粒。反足细胞形成后不久即退化。助细胞具多糖性质的丝状器,受精前两个助细胞退化。卵细胞核对Feulgen反应呈负反应。二极核受精前由胚囊中部移向卵器,与卵器接触后融合形成次生核。发育早期的胚珠为厚珠心,双珠被。晚期,内珠被退化,故成熟胚珠为单珠被。四核胚囊时期,珠孔端珠心组织退化,胚囊伸向珠孔形成胚囊喙。合点端珠心组织含丰富的蛋白质和核酸,这一性质与绒毡层性质相似,可能涉及胚囊的营养运输。胚囊的营养来源于子房和胎座细胞内贮存的淀粉粒。     

唇精子早期入卵观察

用扫描电镜对唇成熟卵子及早期精子入卵过程进行观察.结果 显示,唇成熟卵子在动物极中央有一深凹陷的表面光滑的精孔器,其外径2.512 μm,内径2.330 μm,精子直径1.567 μm.混匀的精卵刚遇水时,没有精子进入精孔器.受精后1 s,精孔器内出现精子.受精后5 s,组织切片显示,精子已经进入卵子内,并形成具有强烈抑制多精入卵作用的受精锥.受精后10 s,精子在精孔器前庭集结,尚未形成受精塞.受精后20 s,在精孔器内形成受精塞.受精塞没有阻塞精孔管,经分析它不是来源于皮层反应产物.受精塞形成后,可以吸附入卵的精子,这对多精入卵有积极的抑制作用;精子尾部在入卵过程中相互缠绕,这也是减少多精入卵的重要机制.受精后30 s, 受精塞和吸附的精子向精孔器外移动.受精后50 s, 受精塞和吸附的精子堵塞精孔器.受精后60 s, 受精塞吸附的精子开始解体,但是由于精孔管未封闭,还有精子通过精孔管进入到质膜.在人工受精过程中,卵子的单精受精屏障会因其周围精子密度大、精子与卵子距离短、精子运动速度快而被打破,从而导致这些卵子出现多精入卵的现象.受精后80 s, 精孔管仍然没有封闭,精孔器附近的精子明显出现活动能力的差异:精孔器外面的精子活动能力最强,精孔管旁边的精子活动能力较弱;精孔管外堆积的精子活性消失,受精塞吸附的精子已开始解体,经初步分析,这可能是进入其内的精子耗能有所差异的结果.受精后100 s,受精塞吸附的精子解体.     

多胚水稻品系APⅣ不同类型胶囊的受精及其胚胎形成

通过GMA半薄切片技术对APⅣ不同类型水稻(Oryza sativa L.)胚囊的受精及其胚胎发育的研究表明,APⅣ中5-2-l型胚囊的3个卵细胞在少数情况下都可受精并发育形成3个胚;但多数情况只有 1个或2个卵细胞受精发育成1个胚或2个胚。6-2-0型和5-3-0型胚囊多个卵受精频率都很低。由此证明APIV多胚是来自如5-2-1型胚囊的多卵卵器胚囊多个卵细胞都受精的结果,其中3胚来自3个卵细胞受精发育,2胚来自2个卵细胞受精发育。双套结构胚囊受精最为复杂,多数情况是受精不正常,只有少数子房大、小胚囊中的卵细胞都能正常受精。大胚囊中的卵细胞受精发育可能是形成所谓中位胚(远离珠孔端胚)的主要原因。     

Origin of Megagametophytes with Supernumerary Egg Cells Occurring in Oryza sativa

Cytoembryological observations were attempted to reveal the cytological origin of megagametophyte with supernumerary egg cells. It was shown that all ovules underwent a normal megasporogenesis. The meiosis of megasporocyte consisted of two successive divisions, which gave rise to four haploid megaspores. It was the chalazal spore that developed to form the megagametophyte while the three micropylar megaspores degenerated quickly. After first mitosis in the functional megaspore the two nuclei were separated to the micropylar and chalazal poles by a large central vacuole, meanwhile a differential enlargement of the two-nucleate embryo sac was visualized. The micropylar side enlarged quickly and in contrast, the chalazal side remains almost unchanged. Immediately afterward, the second mitosis took place forming four-nucleate embryo sac. During the second mitosis, nucleus located in the narrow area of chalazal side divided transversely, with its upper sister nucleus migrating to the central or micropylar part of the embryo sac, while the nucleus in the micropylar side divided at an angle of about 45° against the micropylar-chalazal axis. Through the third mitosis, two patterns of nuclear arrangement deviating from polygonum were observed. (i) One nuclear distribution pattern was two, two, four respectively in chalazal, central and micropylar parts. And during maturation the four micropylar nuclei differentiated as egg apparatus consisting of two egg cells and two synergids. The two central nuclei, which presumably suppressed the movement of nucleus toward centre part from both micropylar and chalazal sides developed into central cell with two polar nuclei. And the two chalazal nuclei organized into antipodal cells. Rarely indeed, one nucleus of either chalazal or micropyle side did migrate to join the formation of central cell. (ii) The other nuclei arrangement pattern was two and six respectively positioned in chalazal and micropylar sides. During maturation, five micropylar nuclei differentiated into egg apparatus consisted of three egg cells and two synergids. The sixth one migrated to form the upper polar nucleus. The lower nucleus of the chalazal side developed into antipodal cell which divided quickly, and the upper nucleus became the lower polar nucleus.     

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.     

葱的无丝分裂和核物质穿壁运动的细胞胚胎学研究

1.核穿壁运动一般系经胞间联丝的孔道,但是,有时核仁突破细胞壁,核物质经由该破裂的小孔转移,间或细胞壁先行溶解或破裂,于是核物质胞间转移自无障碍。所以胞间联丝的孔道是核穿壁一般的,而非唯一的,必然的通道。2.乾置的葱叶及成熟花粉,核物质穿壁频繁,而花粉发芽时,花粉管内的核物质穿出侧壁例甚罕见。由此,吸水,有氧呼吸,并非核物质穿壁的先决条件。细胞质川流对温度很敏感,而核物质(包括核液与染色质)穿壁,对 温度不敏感。细胞质川流有一定方向,而核物质穿壁无一定方向。细胞质川流只限于胞间内,而核物质穿壁有穿出有机体外。所以细胞质川流或核液川流作为核物质穿壁运动的推动力,难于成立。     

韭菜胚囊发育与胚胎发生

韭菜胚囊发育为葱型,胚胎发生属柳叶菜型。成熟胚囊中,三个反足细胞形态上常类似卵器,其中二个呈助细胞状,一个呈卵细胞状。卵状反足细胞可分裂成多细胞原胚,但随着胚乳的发育而退化。在未受精胚囊中,卵细胞和卵状反足细胞均可分裂,它们的发生过程与合子胚相似,但因无胚乳哺育,均不能继续发育。论证了反足细胞胚的性质,初步探讨了胚乳与反足细胞无配子生殖的关系。     

Polyspermy and fertilization of antipodals in Lilium (Tourn.) L. Species

It is found that several pollen tubes may enter the embryo sac of the lily plant, and that the tubes penetrate the sac from the direction of the antipodal apparatus. One of a pair of sperms of an additional pollen tube copulates with the upper antipodal, and the other with the lower antipodal or the central cell. The process of fertilization of the antipodal is completed in a phase of nuclear morphological similitude typical of the postmitotic type of fertilization. Directed growth of pollen tubes in lily is associated with specific differentiation of cells of the antipodal apparatus that simulate the egg cell.     

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.     

东北地区野豌豆属VICIAL．物种生物学研究Ⅷ．幼苗形体结构动态和种间界限

在野外居群调查的启示下,本文以组件观点对柳叶野豌豆复合种和歪头菜幼苗亚单位的时序变化与开花关系进行了分析。结果发现在柳叶野豌豆复合种栽培居群中存在打破物种间形体结构特征的个体,即在复叶由一对小叶组成的植株就已开花而进入生殖时期。另外,在歪头菜的野生居群中发现由三或四枚小叶组成复叶的个体,因此,我们推测这种形体结构的变化可能暗示着柳叶野豌豆复合种和歪头菜有着共同的祖先。     

芒苞草形态学和胚胎学研究：Ⅱ.花药和胚珠发育的研究

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水稻胚囊超微结构的研究

水稻(Oryza sativa L.)胚囊成熟时,卵细胞的合点端无细胞壁,核居细胞中部,细胞器集中在核周围,液泡分散于细胞周边区域。助细胞珠孔端有丝状器,合点端无壁,核位于细胞中部贴壁处,细胞器主要分布在珠孔端,液泡主要分布在合点端。开花前不久,一个助细胞退化。中央细胞为大液泡所占,两个极核靠近卵器而部分融合,细胞器集中在极核周围和靠近卵器处,与珠心相接的胚囊壁上有发达的内突。反足细胞多个形成群体,其增殖主要依靠无丝分裂与壁的自由生长,反足细胞含丰富活跃的细胞器,与珠心相接的壁上有发达的内突。开花后6小时双受精已完成,合子和两个助细胞合点端均形成完整壁。合子中开始形成多聚核糖体、液泡减小。退化助细胞含花粉管释放的物质,其合点端迴抱合子。极核已分裂成数个胚乳游离核,中央细胞中细胞器呈活化状态。反足细胞仍在继续增殖。讨论了卵细胞的极性、助细胞的退化、卵器与中央细胞间界壁的变化、反足细胞的分裂特点等问题。