The transmitting tract in Trimezia fosteriana (Iridaceae). 1. Ultrastructure in the stigma, style and ovary

An ultrastructural investigation of the entire transmitting tract in Trimezia fosteriana (Iridaceae) was undertaken. The transmitting tissue is secretory but transfer cells do not occur at any level. With exception for the stigma papillae, the cells are covered with large amounts of secretory products. The papillae have a thick and ridged cuticle. The cuticle in the rest of the transmitting tract is thin and detached from the cell wall by the secretory products. It is more or less ruptured in the secretory parts of the stigma and ovary. In the stylar canal the major part of the cuticle is continuous and covers the secretory products. The occurence of a large amount of vesicles in the stigma transmitting tissue cells is interpreted as a result of high dictyosome activity. An electron opaque material is produced in the dictyosomes and appears in vesicles and vacuoles but also between the plasma membrane and the cell walls in the stigma. A small amount of such material is present in the cell walls. Corresponding material is also present in the style and the ovary but declines basipetally. Plastids with strongly electron opaque plastoglobules are present at all levels in the transmitting tract.     

Histogenesis of the transmitting tract in Strelitzia reginae

Organisation and development of the stigmatic, stylar and ovarian parts of the transmitting tract in Strelitzia reginae were evaluated. They were characterised by 1) cell shape, 2) appearance of distal cell wall, 3) type of plastid, 4) and vacuolar system. The long stigmatic trichomes have a secondary irregular wall layer separated from the primary wall. Cell structures include pleomorphic plastids with vesiculated thylakoids and frequently a crystal or a lipidic globule. In early stages of bud development the extensive endoplasmic reticulum (ER) is smooth, whereas it is mainly rough in older buds. Coated vesicles are frequent, as are dictyosomes. Prominent invaginations along the plasma membrane contain floccular deposits in the older flower buds. These deposits are similar in structural appearance to material in the large vacuoles. The basal part of the stigma has wedge-shaped cells with wall ingrowths. Three stages of stigmatic secretion during the development were characterised. The stylar canal is initially narrow but widens subsequently. The cuticle is detached and the apical cell walls show a fringed surface; from this wall inbuddings develop shortly before anthesis. At this stage sheets of rough ER are evident in the cell cortex. The plastids have a few vesiculated thylakoids, proteinaceous crystals and starch grains. The epithelial cells of young buds have numerous vacuoles, the volume of which decreases in more mature cells. The stylar canal is filled with a secretion at all stages of bud development. The face of the ovarian transmitting tract, lining the placenta, is smooth in young buds but lobed in older ones due to the division pattern of the epithelial cells. These cells are large, elongated and culumnar as young but narrow and wedge-shaped when more mature. Cell wall inbuddings are formed late during bud development.     

Developmental Aspects of Ultrastructure, Histochemistry and Receptivity of the Stigma of Nicotiana sylvestris

The bilobed papillate stigma of Nicotiana sylvestris Speg. andComes, is covered at maturity with a copious exudate containinglipid, protein and carbohydrate. The stigma is receptive fromthe very early stage of development and it also stains positivelyfor esterase activity. The stigma has three distinct zones:an epidermis with papillae; a subepidermal secretory zone; anda parenchymatous ground tissue. The behaviour of the cells ofthese three zones has been followed from 6 d before anthesisto one day after anthesis and pollination. The cells of theepidermis and the secretory zone stain intensively for lipids,proteins and carbohydrates in the initial stages. The secretoryzone develops large intercellular spaces containing heterogenoussecretory products which also stain positively for the aforesaidthree compounds. At maturity the secretory products are releasedto the surface through gaps formed in the epidermis by cellseparation. The main secretion of the stigma is produced bythe cells of the secretory zone. Less secretion is derived fromthe stigmatic papillae. Some amount of secretion is also releasedfrom the stylar transmitting tissue adjoining the stigma. Theglandular cells of the stigma contain numerous plastids, mitochondria,ribosomes, ER, cytoplasmic lipid droplets and some dictyosomes.The plastids and the vacuoles in the secretory cells of thestigma have a lot of electron dense (osmiophilic) inclusionsrespectively in the initial and later stages of development.The former are probably involved in the production of thesematerials. It is suggested that the proteins are directly secretedby rough ER compartments whereas smooth ER is involved in thesynthesis of lipidic materials. The carbohydrate moiety of theexudate is released by the eccrine mode (sugar mono- and dimers)with some addition of polymers by disintegration of the middlelamellae. The means by which the lipidic and osmiophilic materialis extruded remains unclear. Nicotiana sylvestris, stigma receptivity, organization, stigmatic secretory system, stigmatic exudate     

贯叶金丝桃叶中分泌细胞团的超微结构

随着贯叶金丝桃（Hypericum perforatum L.)叶中分泌细胞团的发育,其细胞中质体的数量和体积逐渐增大,但一些质体局部出现解体,大量的深色管状结构和小泡出现在退化质体的周围,有些小泡与液泡融合,并将其内容物释放至液泡中,导致液泡中出现大量的多泡结构,多膜结构和嗜锇滴。同时,高尔基体分泌小泡进入液泡。然而,当分泌细胞团发育成熟后,分泌细胞被含有灰色均匀的分泌物（金丝桃素）的大液泡所占据,嗜锇滴消失。表明嗜锇滴可能是金丝桃素的前体物,来源于退化的质体。出现于质体和嗜锇滴之间的内质网和高尔基体可能也参与了金丝桃素前体物的合成和细胞内的转运。     

GYNOECIAL DEVELOPMENT,POLLINATION, AND THE PATH OF POLLEN TUBE GROWTH IN THE TEPARY BEAN,PHASEOLUS ACUTIFOLIUS

The gynoecium of Phaseolus acutifolius var. latifolius, a self-compatible legume, is characterized by a wet non-papillate stigma, an intermeditae hollow/solid style type, and secretory cells on the ventral surface of the ovary which direct pollen tube growth. The stigma is initially receptive 5–6 days prior to anthesis. Production of stigmatic secretions, composed primarily of carbohydrates and lipids, fragment the cuticle covering epidermal cells of the stigma early in ontogeny; the lipidic aspect of the copious secretions apparently serves to inhibit desiccation after the cuticle is ruptured. Stylar canal development occurs as a combination of elongation of a basal canal present early in development, and dissolution of part of a solid transmitting tract tissue just below the stigma. Anthers dehisce and the tricolporate pollen is released onto the receptive stigma one day before anthesis. Following initial growth in intercellular spaces in the transmitting tract of the stigma, pollen tubes adhere to epidermal secretory cells along the ventral side of the stylar canal and upper ovary; here the transmitting tract is apparently limited in the number of tubes it can accommodate, providing a possible site of selection of male gametes.     

Reproductive biology of Nymphaea capensis Thunb. var. zanxibariensis (Casp.) Verdc. (Nymphaeaceae)

Anthesis in Nymphaea capensis var. zanzibariensis is diurnal with flowers opening and closing for three consecutive days. On the first day of anthesis, the stigmatic papillae secrete fluid and the outermost anthers are dehiscent. On the second day of anthesis the stamens form a cone above the dry stigmatic cup. The middle stamens open and turn outward. On the third day of flowering, all the stamens open and the dry stigmatic cup is exposed. The flowers are homogamous and not protogynous as the other Nymphaea. The gynoecium of the self-compatible N. capensis var. zanzibariensis , is characterized by a wet papillate stigma, a short hollow style, and secretory cells on the ventral surface of the ovary. The pollen is released on the receptive stigma. Following initial growth in intercellular spaces in the transmitting tract of the stigma, pollen tubes travel through the stylar canal and into the ovary.     

Cotton embryogenesis: The pollen cytoplasm

Summary The ultrastructure and composition of cotton (Gossypium hirsutum) pollen, exclusive of the wall, was examined immediately before and after germination. The pollen grain before germination consists of two parts: the outer layer and a central core. The outer layer contains large numbers of mitochondria and dictyosomes as well as endoplasmic reticulum (ER). The core contains units made of spherical pockets of ER which are lined with lipid droplets and filled with small vesicles; the ER is rich in protein and may contain carbohydrate while the vesicles are filled with carbohydrate. Starch-containing plastids are also present in the core as are small vacuoles. The cytoplasm of the pore regions contains many 0.5 spherical bodies containing carbohydrate. After germination the ER pockets open and the lipid droplets and small vesicles mix with the other portions of the cytoplasm. With germination the pore region becomes filled with mitochondria and small vesicles. The vegetative nucleus is large, extremely dense and contains invaginations filled with coils of ER. A greatly reduced nucleolus is present in the generative cell which is surrounded by a carbohydrate wall. The cytoplasm of the generative cell is dense and contains many ribosomes, a few dictyosomes and mitochondria, many vesicles of several sizes, and some ER. No plastids were identified. The generative nucleus is also dense with masses of DNA clumped near the nuclear membrane. An unusual tubular structure of unknown origin or function was observed in the generative cell.     

Ultrastructural Aspects of the Nectary Spur of Limodorum abortivum (L) Sw. (Orchidaceae)

The ultrastructure of the nectary spur of Limodorum abortivum(L) Sw. was examined before and after anthesis. In cross sectionthe nectary spur shows an internal epidermal layer of thin-walledcells bordering the secretory cavity and 10–12 layersof parenchyma cells. The ultrastructure of the secretory cellssuggests the involvement of ER, Golgi and plastids in nectarsecretion. The nectar accumulated in the sub-cuticular spaceis released into the nectariferous cavity by rupture of theouter layer of the cuticle. Limodorum abortivum (L) Sw., Orchidaceae, nectary spur, nectar secretion, ultrastructure, anthesis, endoplasmic reticulum, dictyosomes, plastids     

ULTRASTRUCTURAL AND HISTOCHEMICAL CHARACTERISTICS OF THE STIGMA OF CICER ARIETINUM

The stigma of Cicer arietinum L. cv. UC-5, a self-compatible legume, is comprised of a small central region of papillate cells which exhibit a localized surface secretion at the white bud stage of development, and of surrounding peripheral cells which lack surface secretion at the white bud stage and at anthesis. The cuticle of cells of the central region is thin and smooth and is displaced from subtending cells and fragmented as a result of secretory production. The cuticle of peripheral cells is thick and rugose. Although it is also displaced by secreted material, it is not disrupted during the white bud stage of development or at anthesis. The contents of central and peripheral papillate cells are similar. Cells are densely cytoplasmic, often with starch-containing plastids. Mitochondria, Golgi bodies, and associated vesicles are abundant, along with strands of smooth and rough endoplasmic reticulum. The limited stigma surface area covered by the secretion may restrict pollen capture and retention. This limited area may partly account for the notably unsuccessful hybridization attempts to broaden the genetic base and to develop improved cultivars of Cicer.     

黄瓜雌花发育过程中柱头的腺特征(英文)

利用透射电镜技术研究了黄瓜（Ｃｕｃｕｍｉｓ　ｓａｔｉｖｕｓ　Ｌ．）雌花柱头发育过程中传递组织、分泌组织和乳突细胞的超微结构。在整个发育过程中,乳突细胞和分泌组织细胞的细胞质内密布很多管状及槽库膨大的内质网,产生很多分泌囊泡;在成熟柱头的传递组织和分泌组织细胞间观察到大量的胞间连丝;乳突细胞和分泌细胞高度液泡化,质膜内折;在柱头发育过程中分泌组织细胞的核周腔扩大形成裂瓣状核,到柱头成熟阶段裂瓣状核更加明显。进一步的研究显示,在成熟柱头的不同组织细胞中,　ＡＴＰａｓｅ的活性呈现在质膜和液泡膜上,随着柱头的发育,ＰＭ－Ｈ＋－ＡＴＰａｓｅ的比活性明显增强。结果表明,黄瓜雌花柱头的腺特征随发育进程而趋于显著。     

Structure and cytochemistry of the procambium in Salix buds during dormancy and dormancy breaking

This report presents a combined investigation of ultrastructural and enzymatic changes in the procambium from late winter to early spring. In January the procambial cells of dormant Salix buds have a convoluted plasma membrane with many plasmalemmasomes, numerous lipid bodies, large stacks of rough ER and plastids surrounded by smooth ER profiles. Several small lysosomes show activity of ATPase and acid phosphatases. In addition ER, nuclear envelopes, dictyosomes, and thylakoids have ATPase activity, and ER and plasmalemma, and nuclei also show acid phosphatase activity. In February metabolism seems to increase as indicated by lysosomes with membranous formations, dilated ER, nuclear envelopes, spiny vesicles, and polysomes. ATPase activity occurs in plasmalemma and vacuoles, and acid phosphatases in the middle lamella region of walls, in plasmalemma, vacuoles, ER, and nuclei. At the end of March, when growth starts inside the buds, but before they break, the stacks of rough ER disappear, and the vacuoles coalesce. Most of the lipid bodies have disappeared and the plastids have accumulated starch. Cell division and differentiation of procambial cells to protophloem and protoxylem have started. The distribution of ATPase increases; activity is found in walls and plasmalemma, and only a few small vacuoles still have ATPase and acid phosphatase activity. Notable is the appearance of ATPase in mitochondrial cristae and nucleoli and the occurrence of rather high levels also in endomembranes and dictyosomes.     

黄瓜雌花发育过程中柱头的腺特征

利用透射电镜技术研究了黄瓜(Cucumis sativus L.)雌花柱头发育过程中传递组织、分泌组织和乳突细胞的超微结构.在整个发育过程中,乳突细胞和分泌组织细胞的细胞质内密布很多管状及槽库膨大的内质网,产生很多分泌囊泡;在成熟柱头的传递组织和分泌组织细胞间观察到大量的胞间连丝;乳突细胞和分泌细胞高度液泡化,质膜内折;在柱头发育过程中分泌组织细胞的核周腔扩大形成裂瓣状核,到柱头成熟阶段裂瓣状核更加明显.进一步的研究显示,在成熟柱头的不同组织细胞中,ATPase的活性呈现在质膜和液泡膜上,随着柱头的发育,PM-H -ATPase的比活性明显增强.结果表明,黄瓜雌花柱头的腺特征随发育进程而趋于显著.     

THE ULTRASTRUCTURE OF CARPOSPOROGENESIS IN CALOGLOSSA LEPRIEURII (DELESSERIACEAE,CERAMIALES)

Carposporogenesis in Caloglossa leprieurii is divided into three cytological stages. At stage I, the young spores have few plastids and little starch. Abundant dictyosomes secrete a gelatinous wall layer in scale-like units. At stage II, dictyosomes produce a second fibrillar wall component in addition to the gelatinous constituent. Large fibrillar vesicles accumulate in the cytoplasm. Production of gelatinous material decreases in this stage. By stage III, starch grains and fully developed plastids are abundant. Rough endoplasmic reticulum occupies much of the peripheral cytoplasm. A dense, granular proteinaceous component appears in the wall in association with the fibrillar layer. Arrays of randomly oriented tubules are scattered in the cytoplasm. The mature carpospore is surrounded by an outer gelatinous wall layer and an inner fibrillar layer. Few dictyosomes persist in the mature spore. Carposporogenesis in Caloglossa is compared with that in other red algae.     

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.     

Studies of pollen maturation in cotton: the storage reserve accumulation phase

Summary This study follows the maturation of the pollen grain of cotton (Gossypium hirsutum L.), particularly the development of the vegetative cytoplasm and the various storage products formed. CTEM, HVEM, stereoscopy, and cyto-histochemistry were used to examine the events occurring during the 9 days before anthesis. Starch began to accumulate in plastids at anthesis minus 9 days and reached a peak concentration shortly before anthesis; lipid deposition followed a similar pattern, but started at 6 days before anthesis. Lipid bodies were always seen closely oppressed to the endoplasmic reticulum (ER). Dictyosomes appear active during the entire 9 days; first producing vesicles involved in the formation of the intine and, later, producing vesicles stored in the pollen grain. The dictyosome vesicles appear to contain polysaccharides and concentrate in layers around the lipid bodies. Ribosomes increase in number from 6 days before anthesis and are particularly numerous in the mature pollen. From anthesis minus 6 days until anthesis, the ER cisternae become increasingly inflated and, in the hours immediately before pollen release, form pockets filled with lipid bodies and dictysosome vesicles. The mature pollen has a core region filled with ER pockets and a peripheral cytoplasm in which such pockets are generally lacking.This research was supported in part by NSF Grant BMS575-22-23 and Grant N.RR-00592 from the Division of Research Resources, National Institutes of Health     

STIGMA,STYLE, AND OBTURATOR OF ORNITHOGALUM CAUDATUM (LILIACEAE) AND THEIR FUNCTION IN THE REPRODUCTIVE PROCESS

Transmitting tissue in Ornithogalum is divided into three regions corresponding to classical divisions of the gynoecium: stigma, style, and ovary. The stigma differentiates from epidermal cells of the stylar apex. These cells form the stigmal papillae and have dense cytoplasm with abundant ER and lipid bodies. Papillae have walls with small transfer-ingrowths. At floral receptivity, papillae secrete a small amount of surface exudate. Epidermal cells of the style contain numerous spherosomes and have thin filaments of cytoplasm traversing the central vacuole. The stylar cortex is composed of 3-6 layers of parenchyma cells which contain numerous spherosomes and often have secondary vacuoles. Vascular tissue in the style consists of one collateral bundle in each lobe. Cells of the epidermal layer lining the stylar canal are secretory. They are initially vacuolate but fill progressively with dense cytoplasm as their secretory activity increases. Secretory activity occurs in three phases, each characterized by a particular organelle population and secretory product. At anthesis, the canal is filled with an exudate consisting of carbohydrate, protein, and lipid. In the ovary, the obturator differentiates from cells at the base of the funiculus and the tip of the carpel margins. It forms a pad of tissue which covers most of the former placenta. The obturator is secretory and produces a surface exudate. We believe our observations on Ornithogalum support the hypothesis that all transmitting tissue is of the same morphological origin and that it provides nutritive and chemotropic factors for pollen tube growth.     

烟草花粉萌发和花粉管生长期间柱头和花柱中的钙分布

烟草柱头表面有两层覆盖物,其中含有少量细小的钙颗粒.花粉落到柱头上后,储存在花粉外壁中的钙被释放到覆盖层中.当花粉管穿过覆盖层长入柱头细胞之间时,花粉管顶端的细胞壁中出现了大量的细小钙颗粒.开花后22 h观察时,在花柱引导组织中形成了钙的梯度分布:花柱上部引导组织中的钙较少,而下部连接子房处的花柱引导组织中含有较多的钙颗粒.去雄花开花后1 d时,花柱上部引导组织中的钙明显增多;3 d时,连柱头细胞中也出现了较多的钙颗粒.讨论了烟草花柱引导组织中钙梯度分布和花粉管生长的关系.     

Floral nectary and osmophore of <Emphasis Type="Italic">Epipactis helleborine</Emphasis> (L.) Crantz (Orchidaceae)

The analysis of flowers collected at different stages of anthesis provides strong evidence to conclude that the shell-shaped hypochile and the knobs of epichile form a nectary. The scent comes from the aromatic constituents of nectar and the epichile tissue and the apices of all tepals (osmophores). The comparison between pollinated and unpollinated flowers revealed that the anthesis of unpollinated flowers lasted up to the 16th day. The nectariferous secretory cells formed single-layered epidermis and several layers of underlying parenchyma built by small, isodiametric cells with thin walls and dense cytoplasm, relatively large nuclei, supplied by collateral vascular bundles. During the floral lifespan, the residues of secreted material were higher on the hypochile cells. The lipoid-carbohydrate material and lipid globules in the cell walls and in the cytoplasm were localised. The abundance of starch grains was observed at the beginning of anthesis and their gradual reduction during the flower lifespan. At the end of anthesis in unpollinated flowers, the lipoid-carbohydrate-phenolic materials have been demonstrated. The phenolic material was the same as in plastoglobuli. The features such as irregular plasmalemma, the secretory vesicles that fuse with it, fully developed dictyosomes, numerous profiles of ER indicate vesicle-mediated process of secretion. The substances could be transported by vesicles to the periplasmic space via granulocrine secretion and then to the external surface. Both micro-channels and slightly developed periplasmic space were visible in the hypochile epidermis. This is the first time for anatomical survey of secretory tissue in pollinated and unpollinated flowers of E. helleborine.     

Calcium snapshots in the stigma and style of medlar (Lycium barbarum L.) during pollen germination and pollen tube growth suggest active calcium oscilations

Abstract

The stigma (tip of the pistil) of medlar is wet and covered with stigmatic exudate at anthesis. The exudate contains many vesicles with abundant calcium precipitates. After deposition on the stigma, the pollen grain undergoes hydration, displaying signs of calcium ion (Ca²⁺) transfer from the exudate vesicles into the pollen grains. Calcium precipitates in the pollen cytoplasm are concentrated into small vacuoles that fuse to form large vacuoles, which provide turgor pressure to push the cytoplasm to the apical region of the growing pollen tube. Many calcium precipitates are present in the stylar transmitting tract, which displays a calcium gradient: fewer precipitates are localised in the distal (upper) transmitting tissue below the stigma, and more precipitates are present in the transmitting tract at the style base. The emporal and spatial distribution of calcium in the stigma and style of medlar suggests that it satisfies the demand for calcium in vivo and played some functional significance.