Cell differentiation in microsporangia of Pinus sylvestris. III. Late pachytene

Cycles of hyperactivity were observed in tapetal and microspore mother cells of Pinus sylvestris L. during the pachytene stage of meiosis in microspore mother cells. Hyperactive periods were characterized by dilated rough ER, hypersecretory dictyosomes, autophagic vesicles having one to two sequestration envelopes, and maze-like whor-les of the endomembrane system. The extent and sequence of differentiation differed between the two cell types. During distinct phases of development there was either fi-brillar flocculent or lipoidal material or both within dilations and at cell surfaces. Tapetal cell transfer of material involved endocytotic and exocytotic vesicles and channels opening directly to the cell surface. Dilations of the nuclear envelope of microspore mother cells in late pachytene intruded into the nucleus and, in conjunction with dilated ER, dominated cell profiles. Cellular morphogenesis in a microspo-rangium was seldom synchronous except for intervals of dedifferentiation when plas-modesma-like connections were formed between tapetal cells. Cycles of differentiation and dedifferentiation were correlated each spring season for five years with the progressive change of pachytene chromosomes, suggesting control by a genetic program rather than annual variations in the environment.     

凤仙花花药发育中多糖和脂滴组织化学研究

以不同发育时期的凤仙花花药为实验材料,采用组织化学方法,对花药发育中的结构变化及多糖和脂滴物质分布进行观察。结果表明:(1)凤仙花的花药壁由6层细胞组成,包括1层表皮细胞,2层药室内壁细胞,2层中层细胞和1层绒毡层细胞。其中绒毡层细胞的形态不明显,很难与造孢细胞区分,且在小孢子母细胞时期退化。(2)在小孢子母细胞中出现了一些淀粉粒,但减数分裂后,早期小孢子中的淀粉粒消失,又出现了一些小的脂滴;随着花粉的发育,小孢子形成大液泡,晚期小孢子中的脂滴也消失;小孢子分裂形成二胞花粉后,营养细胞中的大液泡降解、消失,二胞花粉中又开始积累淀粉;接近开花时,成熟花粉中充满细胞质,其中包含了较多的淀粉粒和脂滴。(3)在凤仙花的花药发育中,绒毡层细胞很早退化,为小孢子母细胞和四分体小孢子提供了营养物质;其后的中层细胞退化则为后期花粉发育提供了营养物质。     

杉木雄性不育株与可育株小孢子囊发育的电镜研究

杉木雄性不育属“无花粉型”,败育从无孢原细胞到四分体时期,中层细胞增生,压迫小孢子母细胞,使之养分更加缺乏并引起减数分裂异常。其表皮层和药室内壁细胞中具大量蛋白体,影响了绒毡层对小孢子发育的外源蛋白的供应;表皮层具膜状溶酶体,引起淀粉粒缺乏和酶系统代谢异常;绒毡层发育后期,缺少包被小泡、乌氏体及绒毡层膜,内质同少、短而光滑,严重影响了绒毡层对小孢子母细胞或小孢子养分和合成细胞壁物质的供给;线粒体发育异常,能量代谢减弱,导致小孢子母细胞或小孢子一系列生理活动紊乱及其原生质体解体。     

扁豆绒毡层发育的超微结构研究

应用透射电镜对扁豆绒毡层发育过程进行了研究,主要结果如下：１）首次发现扁豆绒毡层在发育过程中,经历了二交胞质重组（第一次始于减数分裂末期Ⅱ,第二次始于小孢子发育早期）,使绒毡层细胞的活动呈现３个高峰期（即小孢子母细胞减数分裂期、小孢子四分体期一小孢子早期、小孢子晚期－二胞花粉中期）。２绒毡层细胞的分泌作用有３种形式（渗透分泌、胞吐分泌和自溶）。３．首次观察到绒毡层细胞的内切向壁和径向壁经历了两个周     

A Comparative Study of Anther and Pollen Development in Male Fertile and Male. Sterile Green Onion (Allium fistulosum L.)

Anther and pollen development in male-fertile and male-sterile green onions was studied. In the male-fertile line, both meiotic microspore mother ceils and tetrads have a callose wall. Mature pollen grains are 2-celled. The elongated generative cell with two bended ends displays a PAS positive cell wall. The tapetum has the character of both secretory and invasive types. From microspore stage onwards, many oil bodies or masses accumulate in the cytoplasm of the tapetal cells. The tapetum degenerates at middle 2-celled pollen stage. In male-sterile line, meiosis in microspore mother cells proceeds normally to form the tetrads. Pollen abortion occurs at microspore with vacuole stage. Two types of pollen abortion were observed. In type I, the protoplasts of the microspores contract and gradually disintegrate. At the same time the cytoplasm of microspores accumulates oil bodies which remain in the empty pollen. The tapetal cells behave normally up to the microspore stage and early stage of microspore abortion, but contain fewer oil bodies or masses than those in the male-fertilt line. At late stage of microspore abortion, three forms of the tapetal ceils can be observed: (1) the tapetal cells with degenerating protoplasts become flattened, (2) the tapetal cells enlarge but protoplasts retractor, (3) the cells break down and tile middle layer enlarges. In type Ⅱ, the cytoplasm degenerates earlier than the nucleus of the microspores and no protoplast is found in the anther locule. There are fibrous thickenings iii the endothecium of both types. It is difficult to verify whether the tapetum behavior and pollen abortion is the cause or the effect.     

POLLEN AND TAPETUM DEVELOPMENT IN DESMODIUM GLUTINOSUM AND D. ILLINOENSE (PAPILIONOIDEAE; LEGUMINOSAE)

Each of the four microsporangia has three or four wall layers, a uninucleate tapetum of various cell shapes with nuclei that remain in prophase, and 12-24 pollen mother cells (PMCs). A sterile transverse septum sometimes bisects the microsporangium. PMCs secrete callose but not uniformly, and contact among them continues through meiosis. Simultaneous cytokinesis by furrowing isolates each microspore in callose, which later disperses. The separated microspores become vacuolate, undergo mitosis to become pollen, and later become filled with food reserves. Endothecial wall thickening and tapetal dissolution occur after pollen engorgement. Calcium oxalate crystals form in tapetal cells during the sporogenous stage, reach maximum size during early meiosis, and remain prominent until tapetal dissolution.     

山麦冬大小孢子发生及雌雄配子体发育研究

采用石蜡切片技术对百合科植物山麦冬大小孢子发生及雌雄配子体发育进行了观察研究。结果表明:(1)山麦冬花药具有4个花粉囊,花药壁的发育方式为基本型,花药壁完全分化时由表皮、药室内壁、中层及绒毡层组成。(2)绒毡层发育类型为分泌型,到四分体孢子彼此分离形成单细胞花粉阶段,绒毡层细胞开始解体退化,花粉成熟时绒毡层细胞完全消失;花粉母细胞减数分裂为连续型,四分体为左右对称形排列,成熟花粉为3-细胞花粉,单萌发沟。(3)子房3室,每室2枚胚珠,胚珠倒生型,双珠被,薄珠心,雌性孢原细胞不经过平周分裂而直接发育而成大孢子母细胞。(4)减数分裂后四分体大孢子呈线型或T型排列,合点端大孢子分化为功能大孢子,胚囊发育为蓼型;花粉母细胞减数分裂过程中,二分体、四分体细胞外方被胼胝质壁所包被,小孢子形成后胼胝质壁逐渐消失。该研究结果丰富了百合科植物生殖生物学研究的内容,也为探讨百合科植物的系统学研究提供了参考。     

白菜核雄性不育花药超微结构的研究

对白菜核雄性不育两用系的可育与不育花药进行了超微结构的比较观察。结果显示不育花药的造孢细胞核仁靠边分布:包裹小孢子母细胞的胼胝质厚薄不均匀,不完整等早期异常现象。减数分裂后,四分体细胞中常有多个细胞核。从四分体释放出的小孢子外壁的孢粉素物质不均匀沉积．呈不连续的单层异常结构。最后小孢子通过细胞质收缩方式败育。在可育花药中,绒毡层细胞在小孢子发育后期已显示出退化迹象,同时在细胞中开始积累脂类物质。但在同时期的不育花药中, 绒毡层细胞没有显示出退化的迹象,也不合成脂类物质。从时间上看,败育花药中小孢子母细胞及小孢子的异常在先,绒毡层细胞的异常在后。本研究揭示了白菜核雄性不育花药的超微结构特征, 对我们以前的光学显微镜观察结果予以补充和修正。     

莴苣花药发育过程中钙的分布特征

减数分裂前,莴苣花药中的钙颗粒很少。减数分裂后,花药绒毡层细胞中的钙颗粒明显增加。同时在花药药室基质中也出现许多细小的钙颗粒。刚从四分体中释放出的小孢子内钙颗粒很少。伴随着花粉外壁物质在小孢子表面的沉积,钙颗粒开始积累在花粉壁部位。随后。小孢子中开始出现钙颗粒。当小孢子开始形成液泡后,钙颗粒向其中聚集,伴随着小液泡融合成大液泡。体积较大的钙颗粒主要集中在液泡中,而细胞质基质中的钙颗粒很少。随着二胞花粉中的大液泡消失,花粉细胞质中的钙颗粒变得很少。在以后的发育中,只有花粉壁中积累较多的钙颗粒。在莴苣花药发育过程中,钙与绒毡层细胞的退化和小孢子液泡形成以及二胞花粉中大液泡的消失有关。而花粉外壁表面积累丰富的钙与以后花粉的萌发有关。     

白菜核雄性不育花药超微结构的研究

对白菜核雄性不育两用系的可育与不育花药进行了超微结构的比较观察。结果显示不育花药的造孢细胞核仁靠边分布;包裹小孢子母细胞的胼胝质厚薄不均匀,不完整等早期异常现象。减数分裂后．四分体细胞中常有多个细胞核。从四分体释放出的小孢子外壁的孢粉素物质不均匀沉积,呈不连续的单层异常结构。最后小孢子通过细胞质收缩方式败育。在可育花药中．绒毡层细胞在小孢子发育后期已显示出退化迹象,同时在细胞中开始积累脂类物质。但在同时期的不育花药中．绒毡层细胞没有显示出退化的迹象,也不合成脂类物质。从时间上看,败育花药中小孢子母细胞及小孢子的异常在先,绒毡层细胞的异常在后。本研究揭示了白菜核雄性不育花药的超微结构特征．对我们以前的光学显微镜观察结果予以补充和修正。     

侧柏小孢子囊壁绒毡层和中层细胞的发育

侧柏[Platycladus orientalis (L.)Franco]小孢子囊壁包括3层细胞：表皮、中层和绒毡层。中层细胞为1层扁平的细胞。绒毡尾细胞属于分泌型。成熟的绒毡层细胞除了有单核和双核细胞外,还有三核和四核等多核细胞,细胞核有圆形和长椭圆形2种形态。绒毡层细胞的洒色质伴随着小孢子母细胞减数分裂有一个浓缩和伸展的时期,这个时期影响营养物质向小孢子囊内部转运,绒毡层细胞发育的初期就为造孢细胞提供营养,后期解体时,分泌的乌氏体不是散乱地而是有组织地向花粉粒的表面转移。中层和绒毡层细胞最终作为营养被全部吸收利用。     

Pollen and Tapetum Development in Male Fertile Rosmarinus Officinalis L. (Lamiaceae)

The development of microspores/pollen grains and tapetum was studied in fertile Rosmarinus officinalis L. (Lamiaceae). Most parts of the cell walls of the secretory anther tapetum undergo modifications before and during meiosis: the inner tangential and radial cell walls, and often also the outer tangential and radial wall, acquire a fibrous appearance; these walls become later transformed into a thin poly-saccharidic film, which is finally dissolved after microspore mitosis. Electron opaque granules found within the fibrous/lamellated tapetal walls consist of sporopollenin-like material, but cannot be interpreted as Ubisch bodies. The middle lamella and the primary wall of the outer tangential and radial tapetal walls remain unmodified, but get covered by an electron opaque, sporopollenin-like layer. Pollenkitt is formed only by lipid droplets from the ground plasma and/or ER profiles, the plastids do not form pollenkitt precursor lipids. Tapetum maturation (“degeneration”) does not take place before late vacuolate stage.

The apertures are determined during meiosis by vesicles or membrane stacks on the surface of the plasma membrane. The procolumellae are conical, but at maturity the columellae are more cylindrical in shape. The columellar bases often fuse, but a genuine foot layer is lacking. The formation of the endexine starts with sporopollenin-accumulating white lines adjacent to the columellar bases. Later, the endexine grows more irregularly by the accumulation of sporopollenin globules. In mature pollen the intine is clearly bilayered.

Generative cells (GCs) and sperm cells contain a comparatively large amount of cytoplasm, and organelles like mitochondria, dictyosomes, ER, and multi-vesicular bodies, but no plastids; GCs and sperms are separated from the vegetative cell only by two plasma membranes.     

七叶树小孢子发生及雄配子体发育研究

用石蜡切片法观察了七叶树花药的发育过程.结果表明:(1)雄蕊花药四室,花药壁完全分化时,从外到内依次是表皮、药室内壁、中层和绒毡层,花药壁发育为基本型.表皮细胞1层,发育过程中始终存在;药室内壁在花药成熟时形成带状纤维层加厚;幼小花药壁的中层3~4层细胞,在花药发育成熟时退化消失;绒毡层1层细胞,发育类型为分泌型,小孢子母细胞减数分裂时绒毡层开始退化解体,花药成熟完全消失,仅剩1层绒毡层膜.每一花药中有多列雄性孢原细胞,发生于幼小花药表皮下方;(2)小孢子母细胞减数分裂为同时型,四分体多呈正四面体排列;减数分裂过程中,小孢子母细胞外方被胼胝质壁所包被,小孢子形成后胼胝质壁逐渐消失.成熟花粉二细胞型,外形呈圆三角状,具三孔沟.     

Characterization of fibrous compound of Golgi vesicles in tapetal cells ofDelphinium

Summary It was shown that Golgi structures abundantly appearing in tapetal cells ofDelphinium Ajacis L. developing anthers, prior to meiocytes meiosis, show a fine fibrous material within their vesicles. At the time of the formation of tapetal cell wall this fibrous component, released by an exocytotic process, is incorporated into the cell wall. The membrane of dictyosomes derived vesicles participates in the development of plasma membrane. Fibrous material appears to be morphologically similar to the fibrils of tapetal cell wall; this cell wall gives a positive reaction for cellulose and pectins, as visible in the light microscope. Moreover, the fibrous and pectinase resistant compound of dictyosomes derived vesicles and the fibrils of cell wall disappear partly after cellulase digestion which proves their cellulosic character. On the other hand pectinase treatment as well as ruthenium red staining suggest associated with cellulose pectins within Golgi vesicles.     

白菜细胞核雄性不育花药的细胞化学观察

对一种由一对隐性基因控制的白菜细胞核雄性不育和可育株的花药进行了细胞学和组织化学研究。种子播种后,有1／4植株为不育株,其余的为可育株。通过对不育株和可育株花药发育的细胞学观察,确认不育花粉的败育发生在小孢子发育时期。用组织化学的方法研究了可育株和不育株花药发育过程中的多糖和脂类的分布动态,发现在减数分裂前,可育花药和不育花药的药隔细胞中都储藏了大量的淀粉粒。二者的差异仅是不育花药的绒毡层细胞液泡化明显。在减数分裂后的小孢子发育时期,可育花药的绒毡层细胞具有将药隔细胞中的淀粉粒多糖吸收并转化成脂类的功能,小孢子及以后的二胞花粉中也积累了大量的脂类储藏物质。在不育花药中,虽然减数分裂后药隔细胞中的淀粉粒也都消失,但绒毡层细胞中的脂类物质相比很少,同时绒毡层细胞显示了明显的多糖反应,表明不育花药的绒毡层细胞将糖类转化为脂类的功能受阻。在小孢子的表面有些脂类物质,但在细胞质中却没有脂类积累。这一结果暗示在该种白菜细胞核雄性不育株中,由于花药绒毡层细胞转换多糖为脂类的功能失常,导致了小孢子的败育。     

Cell differentiation in microsporangia of Pinus sylvestris. V. Diakinesis to tetrad formation

Following the diffuse stage, the progression of meiosis in Pinus sylvestris unlike that earlier in meiosis, was conspicuously asynchronous. During the diffuse stage of meiosis tapetal cells dedifferentiated. Plasmodesmata were formed, the cells developed a uniform, meristematic appearance and the nuclei underwent mitosis. Throughout the stages covered by this report tapetal cells redifferentiated, again becoming hypersecretory cells, and Ubisch bodies (orbicules) formed. In angio-sperms Ubisch bodies apparently form only once whereas in Pinus they are produced several or many times with a different and characteristic form each time. The future Ubisch bodies are filled from connections with cisternae of the endoplasmic reticu-lum, then coated by plasma membrane and its glycocalyx. The plasma membrane and glycocalyx coating are likely to be responsible for the specific exine form of Ubisch bodies. Cytokinesis after meiosis was typical of plant cells, but no cell wall formed. Thus deep invasions of callose between microspores give an appearance of furrowing, as was often suggested in classical literature.     

ULTRASTRUCTURE AND DEVELOPMENT OF THE MICROSPORANGIUM OF PSEUDOTSUGA MENZIESII (MIRB.) FRANCO. I. DORMANT STAGES

The dormant (mid-November to mid-February) microsporangia of Pseudotsuga menziesii (Douglas-fir) contain pollen mother cells (PMC's) in diffuse diplotene, surrounded by 1–2 layers of tapetal cells and 3–4 layers of microsporangial wall cells. At the beginning of dormancy, PMC's are large and their walls are lysed. The cell walls contain a thick layer of loosely-arranged fibrils which are produced in large vesicles in the PMC cytoplasm and are secreted across the plasma membrane. PMC's contain several layers of rough ER. The inner tangential and the radial walls of the tapetal cells are lysed. During dormancy the PMC's form many new autophagic vacuoles, the chromatin consists of a network of fine threads comprised of medium-sized granules of uniform size and the nucleoli split. The outer tapetal wall is thick and becomes encrusted by an irregular lipid layer. The tapetal cytoplasm is similar to the PMC cytoplasm but is devoid of amyloplasts. The tapetal cytoplasm shows secretory activity at the beginning of dormancy and again near the end of dormancy. The later secretory activity results in the deposition of a spongy material, especially along the radial and inner walls of the tapetal cells. Tapetal cells contain 1–2 large nuclei which show prominent and irregular clumps of chromatin. Subcellular developmental changes occur in the dormant microsporangia of Pseudotsuga in much the same manner as has been reported for Pinus.     

洋葱花药发育过程中的细胞化学研究(简报)

高等植物花药结构复杂,其发育更是一个迅速、多变的过程,如小孢子母细胞减数分裂期间的细胞质改组、胼胝质壁的形成与降解、大液泡的形成与消失、花粉内外壁的形成、绒毡层细胞的降解、营养物质的积累与转化等。除了上述花药组成细胞的形态和结构发生明显变化外。花药发育的另一个显著特点是以花粉为中心的营养物质单向运输和转化,尤其是小孢子有丝分裂形成二胞花粉后开始积累大量的营养储存物以供成熟花粉萌发时利用。     

MALE STERILITY IN SOYBEAN (GLYCINE MAX). I. PHENOTYPIC EXPRESSION OF THE ms2 MUTANT

The effects of a nuclear male-sterile mutant (ms2) of soybean, Glycine max (L.) Merr., on anther development were analyzed by means of light- and electron-microscopy. The structure of microspore mother cells (MMCs) in male-sterile plants was identical to that of male-fertile plants. Meiosis was completed, and tetrads of microspores formed. Microspores degenerated after the deposition of primexine and probacullae. The sheath of callose surrounding microspores did not dissolve. No structural abnormalities of the microspores were detected before the onset of degeneration. The tapetal and anther wall layers were characterized by aberrant development. Tapetal abnormalities included premature vacuolation, a persistent inner tangential cell wall, failure to differentiate normal concentrations of endoplasmic reticulum and dictyosomes, disruption of plastids, and premature degeneration. Malfunction of the tapetal layer preceded, and may have induced, microspore degeneration. Gross anther morphology was not influenced until advanced stages of development.     

莴苣花药发育过程中钙的分布特征

减数分裂前,莴苣花药中的钙颗粒很少。减数分裂后,花药绒毡层细胞中的钙颗粒明显增加, 同时在花药药室基质中也出现许多细小的钙颗粒。刚从四分体中释放出的小孢子内钙颗粒很少,伴随着花粉外壁物质在小孢子表面的沉积,钙颗粒开始积累在花粉壁部位。随后,小孢子中开始出现钙颗粒。当小孢子开始形成液泡后,钙颗粒向其中聚集,伴随着小液泡融合成大液泡,体积较大的钙颗粒主要集中在液泡中,而细胞质基质中的钙颗粒很少。随着二胞花粉中的大液泡消失,花粉细胞质中的钙颗粒变得很少。在以后的发育中,只有花粉壁中积累较多的钙颗粒。在莴苣花药发育过程中,钙与绒毡层细胞的退化和小孢子液泡形成以及二胞花粉中大波泡的消失有关。而花粉外壁表面积累丰富的钙与以后花粉的萌发有关。