The Ultracytochemical Localization of ATPase Activity in the Ovules of Sunflower

The ultracytochemical localization of ATPase activity was determined employing the method of lead precipitation in the ovules of sunflower (Helianthus annuus L.). No ATPase activity is observed in the egg and synergids except some at the filiform apparatus. Much ATPase activity is localized on the plasma membrane and wall of the central cell. In the antipodal cells, ATPase activity is also found on the plasma membranes, but only a little in their walls. In the integumentary tapetum, besides the plasma membranes, most of the nuclei are rich in ATPase. Between the integumentary tapetum and uncontinuous cuticle surrounding the embryo sac, there is a gap where a lot of ATPase are found. These ATPases are continuously linked with those in the central cell wall throuth the intervals of the cuticle. At the sites of the wall ingrowths of the central celT, abundant vesicles and other structures with high ATPase activity aggregate noticeably in the gap region. According to the ATPase distribution in the ovules, we propose that the whole surface of embryo sac functions in absorbing nutrients directly from the apoplast outside the cuticle, especially via the wall-membrane apparatus of 'he central cell.     

山茶科核果茶属和石笔木属的胚胎学研究

观察了短叶核果茶,石笔木,粗毛石笔木和屏石笔木的大小孢子和雌雄配子体的发生和发育过程,４个种的胚胎学特征高度相似,均为基本型药壁发育,腺质线毡层,同时型小孢子母细胞胞质分裂,四面体形小孢子四分体,二细胞成熟花粉,倒生胚珠,双珠被,薄珠心,单孢原,蓼胚囊,卵细胞与助细胞区分明显,均具有珠被绒毡层和承珠盘,以蓼型胚囊区别于邻近的山茶属。     

金鱼草珠被绒毡层壁囊的分离与鉴定

由金鱼(Antirrhinum majus L.)草开花后的胚珠中分离出抗乙酰解、抗酶解、对强氧化剂有一定抗性但不抗二乙醇胺的细胞壁囊状结构。切片原位观察表明,它是珠被绒毡层的内壁,能被苏丹 IV 染色与金胺 O 荧光染色。它全面地包围胚囊内正在发育的胚和胚乳,仅在合点与珠孔两端开口,而在此二处分别有胚乳吸器与胚柄与外相通。这一结构的功能可能是保证营养物质定向导入胚囊以及防止珠被绒毡层分泌的水解酶侵蚀胚囊等。     

藏药椭圆叶花锚的胚胎学

本文首次报道了藏药椭圆叶花锚的胚胎学特征。花药四室,药壁发育为双子叶型;绒毡层异型起源,腺质型绒毡层。小孢子母细胞减数分裂为同时型,四分体的排列方式为四面体型;成熟花粉为３－细胞。子房２心皮,而二心皮连接处强烈膨大、内凸,４列胚珠。薄珠心,单珠被,直生胚珠。胚囊发育为蓼型。胚乳发育为核型。胚胎发育为茄型酸浆Ｉ变型。反足细胞在胚囊成熟时期宿存。承珠盘发达。果实成熟时,种子只发育至球型胚阶段。比较了该种与龙胆族其它属、种的胚胎学特征,发现它们大部分特征是相似的,但在如下３个特征上存在区别：子房二心皮连接处强烈膨大、内凸;直生胚珠;具有发达的承珠盘。其胚胎学特征的系统学和分类学意义有待进一步比较与评价     

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。     

Cytopathology of Mature Ovaries from Lettuce Plants Infected by Lettuce Mosaic Potyvirus

The location of lettuce mosaic potyvirus (LMV) in mature ovaries of lettuce plants ( Lactuca sativa ) was studied by conventional thin-section electron microscopy and immunogold cytochemistry. Flexuous filamentous particles and inclusion bodies characteristic of LMV infection were observed in the integumentary tapetum, integument and ovary wall of the mature ovary but not in the embryo sac.     

BIOCHEMICAL DETERMINATION OF Mg2+, K+-DEPENDENT,DIETHYLSTILBESTROL-INHIBITED PHOSPHATASE ACTIVITY IN THE OVULES OF SAINTPAULIA IONANTHA BEFORE FERTILIZATION

The occurrence of phosphatase activity that was dependent on Mg²⁺ and K⁺ and inhibited by diethylstilbestrol has been detected in unfertilized African violet ovules with the use of biochemical techniques. Since cation-dependent phosphatase activity is believed to be involved in ion transport across cell membranes, these results are interpreted as lending indirect support to cytochemical evidence that suggests the innermost integumentary cells of African violet ovules are involved in active transport of solutes to the embryo sac.     

海桐大、小孢子发育及雌、雄配子体形成的研究

利用常规石蜡制片法研究了海桐大、小孢子发生及雌、雄配子体发育的过程。结果显示:(1)小孢子母细胞减数分裂过程中的胞质分裂为连续型,四分孢子为以四面体形为主,四分孢子后期部分小孢子壁皱缩;(2)花药壁由4层结构组成,由外到内为表皮、药室内壁、中层和绒毡层;(3)海桐具多个胚珠,单珠被,薄珠心,胚珠类型为倒生胚珠。大孢子母细胞减数分裂主要形成线形排列的4个大孢子,还具有少有的十字形排列,功能大孢子位于合点端;(4)胚囊发育属单孢型的蓼型,成熟的雌配子体为四细胞五核胚囊。     

宁夏枸杞大孢子发生和雌配子体发育的细胞学研究

采用半薄切片技术和组织化学染色法对宁夏枸杞大孢子发生和雌配子体发育过程中的细胞结构变化及营养物质积累特征进行了观察。结果表明,(1)宁夏枸杞为中轴胎座,多室子房,倒生胚珠,单珠被,薄珠心类型。(2)位于珠心表皮下的孢原细胞可直接发育为大孢子母细胞,减数分裂后形成直线型大孢子四分体,合点端第一个大孢子发育为功能大孢子,胚囊发育类型为蓼型,具有珠被绒毡层。(3)初形成的胚囊外周组织中没有营养物质积累,成熟胚囊时期出现了大量的淀粉粒且呈珠孔端明显多于合点端的极性分布特征。(4)助细胞的珠孔端具有明显的丝状器结构,呈PAS正反应表现出多糖性质,成熟胚囊具有承珠盘结构。     

Ultracytochemical Localization of ATPase Activity in the Degenerating Nucellar Cells of Wheat During Degeneration

Ultracytochemical localization of ATPase activity was carried out using a lead phosphate precipitation technique in the nucellar cells of wheat during degeneration. ATPase was only localized on the plasma membranes of nueellar cells at the. early degenerative stage, then decreased and disappeared at the mid-degenerative stage. Meantime it was also observed in the nuclear chromatin and some cytoplasmic organelles. ATPase activity was only observed in the nuclear chromatin in the extremely degenerated nucellar cells. Two patterns of unclear degeneration was found in the degenerated nucellar cells. A lot of small fragments with ATPase from the degenerated nuclei moved toward the embryo sac. It is suggested that the change of ATPase activity on the plasma membranes is related to the physiological change of nucellar cells, and that in the nuclear chromatin is associated with the stages movement of chromatin during the process of nucellar cells degeneration.     

ULTRACYTOCHEMICAL LOCALIZATION OF PLASMA MEMBRANE-ASSOCIATED PHOSPHATASE ACTIVITY IN DEVELOPING TOBACCO SEEDS

Plasma membrane-associated phosphatase activity was found in integumentary cells of developing tobacco ovules from the megaspore tetrad stage to seed maturity. Enzyme activity is greatest in the innermost layers of the integument from the mature megagametophyte stage on. The egg, zygote, and synergids almost totally lack plasma membrane-associated reaction product, while the antipodals show some activity at their chalazal ends. The endosperm has much plasma membrane-associated phosphatase activity in most of its cells during development, but it is primarily the outermost plasma membranes of the surface cells of the embryo that have associated reaction product. It is concluded that the plasma membrane-associated phosphatase activity is related to active transport of assimilates and that the integument is the most important site of active transport in the young ovule. After fertilization, in addition to the innermost layers of the integument, the endosperm and the outermost cells of the embryo become involved in active transport, which continues to seed maturity.     

开口箭大小孢子发生及雌雄配子体发育

利用石蜡切片技术,对百合科植物开口箭(Tupistra chinensis Baker)大小孢子发生及雌雄配子体发育进程进行胚胎学观察分析,以明确开口箭胚胎发育的特征,为百合科植物的研究提供生殖生物学依据。结果表明:(1)开口箭花药具有4个药室,花药壁的发育方式为基本型,由表皮、药室内壁、中层及绒毡层组成;绒毡层发育类型为分泌型,到四分体花药阶段绒毡层细胞开始解体退化,花药成熟时完全消失。(2)花粉母细胞减数分裂为连续型,依次形成二分体、四分体,四分体为左右对称形;成熟花粉为2-细胞花粉,具单萌发沟。(3)子房3室,倒生型胚珠6枚,双珠被,薄珠心;在花部的分化早期,由珠心顶端表皮下方分化出雌性孢原细胞,孢原细胞经过一次平周分裂形成周缘细胞和造孢细胞,造孢细胞发育为大孢子母细胞;大孢子母细胞第一次减数分裂后形成二分体,珠孔端的二分体孢子退化,合点端的二分体孢子继续第二次分裂,形成两个子细胞依次发育为二核胚囊、四核胚囊和八核胚囊;开口箭的胚囊发育类型为葱型。     

狗枣猕猴桃果实发育的解剖学观察

对狗枣猕猴桃果实发育进行了显微和超微结构观察。其主要过程可分为：1. 早期胚胎发育：多心皮合生子房,通常具16个心室,中轴胎座。中轴上着生大量倒生胚珠,单珠被,具珠被绒毡层。胚囊蓼型。授粉后约2～4h花粉萌发。授粉后约120h花粉管到达胚珠。受精后,初生胚乳核分裂先于合子。胚乳发育为细胞型。2. 果壁：果壁可分为果皮、果肉和果心三部分。果皮较薄,由2～3层薄壁细胞组成。外表面光滑无毛,但覆有角质层,气孔下陷,分布于其中。果肉的大部分由薄壁细胞组成,分大、小两种细胞 ,小细胞含较多淀粉粒,淀粉粒的水解是果实软化的原因之一。果肉薄壁组织细胞还含有叶绿体及两种异细胞,一种异细胞内含物为结晶,普遍存在;另一种含被番红染成红色的絮团状物。果心由维管束和薄壁细胞组成,维管束不发达。3. 种子：种皮外表面呈蜂窝状,种皮较硬,由两层细胞构成。线性直立胚,胚乳发达,主要贮藏物是蛋白质。     

小麦珠心细胞衰退过程中ATP酶的超微细胞化学定位

采用磷酸铅沉淀技术对小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ ）珠心细胞衰退过程进行了ＡＴＰ酶的超微细胞化学定位。初始衰退的珠心细胞,ＡＴＰ酶只定位于细胞膜上,其它部位未见有ＡＴＰ酶活性。衰退中期的珠心细胞,细胞膜上ＡＴＰ酶活性减弱并逐渐消失;细胞核染色质和细胞质中一些细胞器上存在ＡＴＰ酶活性。在严重衰退的珠心细胞中,只在细胞核染色质上存在ＡＴＰ酶活性。珠心细胞的细胞核以两种方式衰退。衰退的细胞核染色质碎片仍存在ＡＴＰ酶活性,并向胚囊方向转移。推测小麦珠心细胞衰退过程中细胞膜上ＡＴＰ酶变化反映了珠心细胞生理状态转变;细胞核染色质上ＡＴＰ酶与其形态变化和运动等有关     

Embryology of Handeliodendron bodinieri (Sapindaceae) and its systematic value: development of male and female gametophytes

Embryological characters of Handeliodendron bodinieri (Sapindaceae) are reported for the first time. Anthers are tetrasporangiate. Cytokinesis in microsporocyte meiosis is of the simultaneous type and the microspore tetrads are tetrahedral. The tapetum is secretory and parietal. Mature pollen is bicellular. The ovary is trilocular. There are two ovules in each locule. The placenta is axile. The ovule is crassinucellate, bitegmic and hemitropous, without hypostase when mature. The development of the embryo sac is of the Polygonum type. The systematic significance of the embryological characters of Handeliodendron bodinieri is discussed.     

Embryological Studies on Narcissus tazetta var. chinensis

Chinese narcissus (Narcissus tazetta var.chinensis Roem) blooms but has no seeds.Embryological studies on the species were conducted to discover the causes of its sterility.Its anther wall is composed of four layers of cells,and its tapetum is of the secretory type.The cytokinesis of microspore mother cells is of the successive type,and the tetrad is tetrahedral.During meiosis of microspore mother cells,some chromosomes lagged,and several micronuclei were found in tetrads.Only 27.7% of the pollen grains contained full cytoplasm,and 1.3% of them germinated in culture medium.No pollen grain,however,could germinate on the stigma.The ovary is trilocular with axile placenta,and the ovules are bitegmic,tenuinucellate,and anatropous.Its embryo sac is of the polygonum type.Most embryo sacs degenerated,and only about 4.5% of the ovules contained a normal embryo sac with an egg cell,two synergids,three antipodal,and a central cell containing two polar nuclei.One reason for the sterility of Chinese narcissus is the abnormality of microsporogenesis and megasporogenesis,in which only a few functional pollen grains and embryo sacs are produced.The other reason is that the pollen grains cannot germinate on the stigma.     

Embryo sac development in Arabidopsis thaliana II. The cytoskeleton during megagametogenesis

The microtubular and actin cytoskeletons have been investigated during megagametogenesis in Arabidopsis thaliana using immunofluorescence labelling of isolated coenocytic and mature embryo sacs. We found both actin and microtubules (MTs) to occur in abundance throughout megagametogenesis and in all constituent cells of the mature embryo sac. During many stages, the patterns of distribution of these cytoskeletal elements are congruent and may prove to be co-aligned. Many changes in the arrays of MTs and microfilaments take place and indicate varying roles of the cytoskeleton in the different stages and cell types of megagametogenesis. Two major populations of MTs recur throughout embryo sac formation: (1) Elaborate nuclear-based networks are found during the two-nucleate and four-nucleate developmental stages as well as in the egg cell. These arrays may function in positioning the nuclei. (2) Cytoplasmic MTs in longitudinal orientation in the two-nucleate embryo sac, synergids and part of the egg cell, or in a reticulate pattern in the four-nucleate embryo sac, egg and central cell probably participate in organization of the cytoplasm. Synergid MTs converge at the filiform apparatus. Preprophase bands of MTs are absent throughout megagametogenesis but phragmoplast arrays occur during cellularization of the embryo sac. Well developed arrays of cortical MTs are restricted to the antipodal cells. A large concentration of MTs in the part of the egg cell adjacent to the synergids is well placed for being involved with sperm cell movement within the degenerative synergid. On the basis of the morphology of the cytoskeleton, we concur with views that the shape of megagametophyte is largely determined by the surrounding tissues, including the integumentary tapetum.     

Improved ultrastructural preservation ofPetunia andBrassica ovules and embryo sacs by high pressure freezing and freeze substitution

Summary In order to improve the ultrastructural preservation of the female gametophyte ofPetunia x hybrida andBrassica napus we tested several cryofixation techniques and compared the results with those of conventional chemical fixation methods. Ovules fixed with glutaraldehyde and osmium tetroxide in the presence or absence of potassium ferrocyanide showed poor cell morphological and ultrastructural preservation. In ovules cryo-fixed by plunging into liquid propane, the cell morphology was well preserved. However, at the ultrastructural level structure-distorting ice crystals were detected in all tissues. Due to the large size of the ovules, cryofixation by plunging in liquid propane is not adequate for ultrastructural studies. In contrast,P. x hybrida andB. napus ovules cryo-fixed by high pressure freezing showed improved cell morphological as well as ultrastructural preservation of the embryo sac and the surrounding integumentary tissues. The contrast of the cellular membranes after freeze substitution with 2% osmium tetroxide and 0.1% uranyl acetate in dry acetone was high. At the ultrastructural level, the most prominent improvements were: straight plasma membranes which were appressed to the cell walls; turgid appearing organelles with smooth surface contours; minimal extraction of cytoplasmic and extracellular substances. In contrast to the chemically fixed ovules, in high pressure frozen ovules numerous microtubules and multivesicular bodies could be distinguished.     

Studies on the Development of Gametophytes in Cornus officinalis (Cornaceae)

The floral bud of Cornus officinalis Sieb. et Zucc. began to differentiate at the end of April. In the beginning of November, female and male gametophytes reached their maturation. The flowers fell off in the following March. The wall of the microsporangium comprised epidermis, endothecium, two or three middle layers and a single layer of amoeboid tapetum with two nuclei. The extra-tapetal membrane was formed during the later stage of the development of anther. Meiosis of microspore mother-cell was normal and cytokinesis was of the simultaneous type. The tetrad was tetrahedral in shape. The mature pollen grains were 2-celled and 3-colporate. The ovule was unitegminous and tenuinucellate. During the development of the ovule, some special structures were formed, e. g. hypostase and obturator which originated from the integument. A single archesporium differentiated immediately below the nucellar epidermis. It functioned directly as the megaspore mother-celL This cell under went meiosis to form a linear tetrad. The chalazal megaspore was functional. The development of the embryo sac was conformed as the polygonum type. Two polar nuclei fused into the secondary nucleus and 'three antipodal cells degenerated soon after the embryo sac reached its maturation, at that time the female gametophyte had become an embryo sac which consisted of only four cells each with a nucleus just before two months of blooming. The nuclei of some synergids located in the chalazal part of the cells. Contrarily, the micropylar past of the synergids were occupied by a large vacuole. The secondary nucleus was usually located in the chalazal part of the embryo sac.     

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。