ULTRASTRUCTURAL DEVELOPMENT OF CAPITATE GLANDULAR HAIRS OF CANNABIS SATIVA L. (CANNABACEAE)

The capitate-sessile and capitate-stalked glands of the glandular secretory system in Cannabis, which are interpreted as lipophilic type glandular hairs, were studied from floral bracts of pistillate plants. These glands develop a flattened multicellular disc of secretory cells, which with the extruded secretory product forms the gland head and the auxiliary cells which support the gland head. The secretory product accumulates beneath a sheath derived from separation of the outer wall surface of the cellular disc. The ultrastructure of secretory cells in pre-secretory stages is characterized by a dense ground plasm, transitory lipid bodies and fibrillar material, and well developed endoplasmic reticulum. Dictyosomes and dictyosome-derived secretory vesicles are present, but never abundant. Secretory stages of gland development are characterized by abundant mitochondria and leucoplasts and by a large vacuolar system. Production of the secretory product is associated with plastids which increase in number and structural complexity. The plastids develop a paracrystalline body which nearly fills the mature plastid. Material interpreted as a secretion appears at the surface of plastids, migrates, and accumulates along the cell surface adjoining the secretory cavity. Extrusion of the material into the secretory cavity occurs directly through the plasma membrane-cell wall barrier.     

杭白芷根的分泌道超微结构与其挥发油分泌的关系

利用光镜及透射电子显微镜技术研究了杭白芷根中分泌道结构及其挥发油的分泌,并重点探讨分泌道中挥发油的分泌过程。结果显示:(1)杭白芷的分泌道是由上皮细胞围绕着的伸长的胞间隙,腔道内贮存着挥发油。(2)分泌道细胞的质体、细胞基质以及线粒体参与挥发油或其前体物质的合成。(3)在分泌道发育的后期,大量小泡与分泌细胞的液泡膜和细胞质膜融合,将其内的物质释放进入空腔。研究认为,杭白芷分泌道中挥发油主要合成部位为质体及细胞基质,之后以扩散渗透或通过膜质小泡与液泡及质膜融合这两种方式分泌到空腔内,丰富的线粒体可能为这一系列过程提供能量。     

Mitochondrial deformation and apocrine secretory mechanism in the rabbit submandibular organ as revealed by electron microscopy

Summary The submandibular organ (a sort of apocrine sweat glands) of the rabbit was observed with the electron microscope. The cell structure of glandular tubules varies depending upon the secretory activity; there are three functional stages. The secretory cells at the resting stage are characterized by low height, absence of secretory substance, and presence of small and slender mitochondria.In the synthesizing stage, enlargement and peculiar deformation of mitochondria are observed. Secretory substance always occurs near the deformed mitochondria. The part of a mitochondrion closely abutting on the secretion mass is extremely thin, and contains longitudinally oriented cristae. Sometimes a direct continuity is observed between the thinned portion of the deformed mitochondria and the mass of secretory substance. It is presumed that the secretion is initially produced in the mitochondria and then discharged from them. The Golgi apparatus and the rough surfaced endoplasmic reticulum may be involved indirectly. Smooth surfaced vesicles, probably related to the transport of raw material, are extremely abundant in the cells of this stage.The development of a generally homogeneous projection into the gland lumen is characteristic of the stage of secretion discharge. The mitochondria are again small and slender, and the secretion is liquefied. At the base of the full-grown projection, cytoplasm is condensed to form a demarcation zone from which the projection may become detached. This mechanism of release of secretory product is quite the same as the so-called apocrine secretory process long postulated by light microscopists.     

Development,structure, and occurrence of secretory trichomes ofPharbitis

Summary Secretory trichomes develop from epidermal cells on the leaf primordia and stem ofPharbitis nil. Following an initial growth phase, trichomes begin active secretion of a protein-carbohydrate mucilage. This mucilage covers the shoot apex and developing leaves ofPharbitis.The secretory cells possess cellular organelles in forms usually associated with actively secreting cells: many mitochondria, an elaborate network of rough endoplasmic reticulum (RER), many free ribosomes, and numerous dictyosomes. The role of the dictyosomes is twofold: 1. dictyosome vesicles bud coated vesicles which transport materials from the cell and, 2. dictyosome vesicles coalesce, forming large storage vesicles. The storage vesicles are surrounded by, and often in contact with, poculiform RER. The RER forms an interconnected network throughout the cytoplasm, extending from the nuclear envelope to the plasmalemma. Distended profiles of RER are frequently in direct contact with the plasmalemma. Thus, inPharbitis secretory trichomes, it is the coated vesicles and RER which are active in secretion export. These findings imply a secretory pathway which deviates from the usual pattern in glandular cells.Predoctoral fellow of National Science Foundation during part of the investigation.     

A post-embedding immunoelectron-microscopic demonstration of apolipoprotein-B-containing lipoprotein particles in hepatocytes of fetal rats

Summary We used the protein-A gold technique to demonstrate the presence of apolipoprotein-B in ultrathin sections of fetal rat liver tissue. It was possible to show for the first time that the electron-dense, osmiophilic particles with diameters of 20–20 nm located within the RER cisternae and Golgi complexes of fetal rat hepatocytes contain apolipoprotein-B components and therefore are lipoproteins. After specific labelling an accumulation of gold label was observed on the RER cisternae, Golgi cisternae and the Golgi-associated secretory vesicles of hepatocytes. The specifity of this labelling pattern was assessed by comparison with cytochemical controls. Our qualitative findings were confirmed by a quantitative analysis of the mean labelling intensity (mean number of gold particles per square micron of the surface area of a particular cellular compartment) on the RER, Golgi complexes, mitochondria, nuclei and the remaining cytoplasm of hepatocytes. It is concluded that the hepatocytes of fetal rats are capable of forming apolipoprotein-B-containing lipoprotein particles. With respect to the size-distribution pattern of the observed intrahepatic lipoprotein particles, we suggest that the hepatocytes of fetal rats produce lipoproteins of the low- and very low-density-lipoprotein type.Abbreviations GA Golgi complex - RER rough endoplasmic reticulum - M mitochondria - N nuclei - LP lipoprotein partieles - L lipid droplet - SV secretory vesicle - BCP blood cell precursor - dm dense intracisternal and intravesicular material - LDL low density lipoproteins - VLDL very low density lipoproteins     

Ultrastructure of the sexual segments of the kidney in male and female lizards,Cnemidophorus l. lemniscatus (L.)

Summary Kidneys of adult male and female lizards were studied by electron microscopy, in order to understand the ultrastructure of the collecting duct and a differentiated part thereof, the sexual segment, which is an important accessory sexual organ. First portion of sexual segment in males: The cells are filled with large secretory granules of a wide range of opacities. The granular endoplasmic reticulum is abundant; basal formations of superimposed flat cisternae are frequent. Distended vesicles and microvesicles prevail in the supranuclear, well developed Golgi apparatus. Evidences indicate that secretion of these cells is holocrine. Second portion of sexual segment in males: All of the secretory granules are apical in location and relatively electron-opaque; they show a denser core. This core is formed by a substance which, after lying in contact with ribosomes, enters the secretory vesicles of the highly developed Golgi apparatus. A lighter substance is then condensed around it. The secretion of the granules is merocrine. The granular endoplasmic reticulum is very abundant in these cells, but basal ergastoplasmic formations are lacking. Sexual segment in females: The cells show features similar to those of the male first portion, but they are smaller. Undifferentiated collecting duct: Most of the cells are mucigenic. They have small ovoid, apical secretory granules. The density of the granules varies from cell to cell; when they are electron-lucent, they exhibit laminar or dotted opaque figures. Moderately developed Golgi apparatus and granular endoplasmic reticulum, as well as elongated mitochondria, occur in mucigenic cells. Intercalated among the latter are non-secretory cells. They have very abundant mitochondria, numerous microvilli, many pinocytic and smooth-membrane vesicles, whereas the organelles participating in synthetic processes are poorly developed; their function is most likely related to active solute transport.     

Ultrastructural morphometric analysis of ameloblasts exposed to fluoride during tooth development

Since a considerable amount of the world population is exposed to high doses of fluoride, it is of special concern to investigate its action mechanisms during dental enamel development. In this study, the toxicity of fluoride in ameloblasts during enamel development was evaluated by means of ultrastructural morphometric analysis. A total of 18 male Wistar rats were distributed into three groups. In Group I, the animals received deionized drinking water ad libitum (negative control) and in Groups II and III, they received sodium fluorided (NaF) drinking water at doses of 7 and 100 ppm ad libitum, respectively, for 6 weeks. Morphometric data were expressed as volume density of the most significant organelles present in the secretory and maturation phases of amelogenesis such as RER, granules, lysosomes, phagic vacuoles, microfilaments and mitochondria. The results showed that the volume density of mitochondria in the 100 ppm experimental group was 29% (P < 0.05) higher than the control group in secretory ameloblasts. No remarkable differences were found in maturation ameloblasts for all organelles evaluated. Taken together, these data indicate that NaF at high doses is able to induce cellular damage in secretory ameloblasts, whereas no noxious effect was observed during maturation stage of amelogenesis as depicted by ultrastructural analysis.     

Vesicular Transport of Extracellular Acid Phosphatases in Yeast Saccharomyces cerevisiae

A method for isolation of secretory vesicles from the yeast Saccharomyces cerevisiae based on the disintegration of protoplasts by osmotic shock followed by separation of the vesicles by centrifugation in a density gradient of Urografin was developed in this study. Two populations of the secretory vesicles that differ in density and shape were separated. Acid phosphatases (EC 3.1.3.2) were used as markers of the secretory vesicles. It was shown that the constitutive acid phosphatase (PHO3 gene product) is mainly transported to the cell surface by a lower density population of vesicles, while the repressible acid phosphatase (a heteromer encoded by PHO5, PHO10, and PHO11 genes) by a vesicle population of higher density. These data provide evidence that at least two pathways of transport of yeast secretory proteins from the place of their synthesis and maturation to the cell surface may exist. To reveal the probable reasons for transport of Pho3p and Pho5p/Pho10p/Pho11p enzymes by two different kinds of vesicles, we isolated vesicles from strains that synthesize the homomeric forms of the repressible acid phosphatase. It was demonstrated that glycoproteins encoded by the PHO10 and/or PHO11 genes could be responsible for the choice of one of the alternative transport pathways of the repressible acid phosphatase. A high correlation coefficient between bud formation and secretion of Pho5p phosphatase and the absence of correlation between bud formation and secretion of minor phosphatases Pho10p and Pho11p suggests different functional roles of the polypeptides that constitute the native repressible acid phosphatase.     

Sequential predator effects across three life stages of the African tree frog, <Emphasis Type="Italic">Hyperolius spinigularis</Emphasis>

While theoretical studies of the timing of key switch points in complex life cycles such as hatching and metamorphosis have stressed the importance of considering multiple stages, most empirical work has focused on a single life stage. However, the relationship between the fitness components of different life stages may be complex. Ontogenetic switch points such as hatching and metamorphosis do not represent new beginnings—carryover effects across stages can arise when environmental effects on the density and/or traits of early ontogenetic stages subsequently alter mortality or growth in later stages. In this study, I examine the effects of egg- and larval-stage predators on larval performance, size at metamorphosis, and post-metamorphic predation in the African tree frog Hyperolius spinigularis. I monitored the density and survival of arboreal H. spinigularis clutches in the field to estimate how much egg-stage predation reduced the input of tadpoles into the pond. I then conducted experiments to determine: (1) how reductions in initial larval density due to egg predators affect larval survival and mass and age at metamorphosis in the presence and absence of aquatic larval predators, dragonfly larvae, and (2) how differences in mass or age at metamorphosis arising from predation in the embryonic and larval environments affect encounters with post-metamorphic predators, fishing spiders. Reduction in larval densities due to egg predation tended to increase per capita larval survival, decrease larval duration and increase mass at metamorphosis. Larval predators decreased larval survival and had density-dependent effects on larval duration and mass at metamorphosis. The combined effects of embryonic and larval-stage predators increased mass at metamorphosis of survivors by 91%. Larger mass at metamorphosis may have immediate fitness benefits, as larger metamorphs had higher survival in encounters with fishing spiders. Thus, the effects of predators early in ontogeny can alter predation risk even two life stages later.     

DNA SYNTHESIS AND CELL TURNOVER IN RANA PIPIENS TADPOLE LIVER DURING SPONTANEOUS METAMORPHOSIS1

The relationship of DNA synthesis and cellular turnover to biochemical differentiation during metamorphosis of R. pipiens liver was investigated. Average DNA/cell was constant at 11.6 pg/ nucleus through stage XXV; but increased during juvenile growth; during metamorphosis stages, changes in total DNA content must correspond to changes in cell number. Rates of DNA synthesis were estimated by rates of ³H-thymidine incorporated into the acid-precipitable fractions, corrected for both precursor uptake into the acid-soluble pool, and for endogenous thymine pool size. DNA content increased steadily from premetamorphosis until late prometamorphosis; at preclimax stages XVIII and XX there were two successive decreases in DNA content of approximately 30%. Fluctuations in synthesis rates preceded corresponding fluctuations in content; DNA synthesis was maximal at stages XVI and XVIII, decreased nearly ten-fold at metamorphic climax, and then gradually rose again during late climax stages. The size of the endogenous thymine pool increased transitorily during spontaneous metamorphosis corresponding to a stage of maximal DNA synthesis. These results indicate that both DNA synthesis and cellular turnover play a significant role in determining net DNA synthesis rates and content during metamorphosis. Metamorphosis of the tadpole liver appears to be associated with both proliferation and cellular death, perhaps a replacement of “larval” by “adult” cells. Metamorphosis of the liver cannot be occuring in a “fixed population of cells” as is commonly assumed. An interpretation of the population dynamics of the metamorphic liver is presented.     

小地老虎变态期间马氏管超微结构与酯酶活性的变化

本实验用光镜和电镜观察了小地老虎Agrotis ypsilon Rottemberg幼虫在变态期间马氏管超微结构的变化及成虫马氏管的重组过程,同时还研究了变态期马氏管酯酶的活性.结果表明:(1)变态期间马氏管外形完整,除至预蛹期隐肾复合体解体外,其余无明显变化.(2)变态期间管壁细胞变化显著.幼虫6龄末期马氏管细胞结构开始变化,主要特点为:细胞质电子密度高,充满了核糖体颗粒,微绒毛萎缩,线粒体从萎缩的微绒毛中退出进入细胞质,基膜内褶破坏.进入预蛹期幼虫马氏管细胞解体:基膜内褶、顶端微绒毛、线粒体及细胞质内的其它细胞器消失,并形成自体吞噬泡,细胞质内仅存细胞核及各种类型的液泡.但是在变态期间因底膜始终存在,故马氏管外形不变;至蛹后期,成虫马氏管细胞在原位重组,基膜内褶由浅变深,微绒毛由短变长,线粒体内嵴从无到有.(3)变态过程中羧酸酯酶和酸性磷酸酯酶的活性变化趋势基本相同,以六龄幼虫最强,预蛹期次之,蛹期最低.     

Morpho–anatomical and ultrastructural analysis of extrafloral nectaries in Inga edulis (Vell.) Mart. (Leguminosae)

The presence of extrafloral nectaries (EFNs) between leaflets is an usual feature in Inga edulis (Vell.) Mart. (Leguminosae). Extrafloral nectaries are secretory structures involved in production of nectar and which serve in the protection of plants against herbivores through association with ants. This study aimed to characterize the EFNs of I. edulis at different developmental stages and describe their morphology, histochemistry and ultrastructure. Leaf fragments, containing secretory structures, were processed according to standard methods for light, scanning and transmission electron microscopy. The EFNs were classified into three stages based on morphology: pre‐secretory, secretory and post‐secretory. The pre‐secretory stage occurs in young leaves, whereas secretory and post‐secretory stages occur in developed and senescent leaves, respectively. The EFNs possess a concave surface and a central cleft in which nectar is accumulated and which was not observed in pre‐secretory EFNs. Histochemical tests identified the presence of sugars, proteins, phenolic compounds, mucilage and lipids at all developmental stages of the EFNs. Calcium crystals were identified in all tissues and stages of the EFNs. The secretory cells of the EFNs exhibit a granular cytoplasm, small vacuoles, prominent nuclei, smooth endoplasmic reticulum and mitochondria. Post‐secretory stage EFNs exhibited intense cytoplasmic degradation and the presence of microorganisms. The performance of EFNs of I. edulis appear to follow the leaf development.     

Isolation of secretory vesicles from Saccharomyces cerevisiae

Purification of secretory vesicles from Saccharomyces cerevisiae has been hindered because these organelles normally represent a small proportion of cellular membranes. In the yeast secretory mutant sec1, secretory vesicles accumulate intracellularly in large quantities. Using a sec1 strain we have devised a procedure for the partial purification of these vesicles. The purification employs differential and density gradient centrifugations and an electrophoretic separation of membranes. The fractions obtained from this procedure are enriched for secretory vesicles at least fivefold over other cellular membranes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of solubilized membrane fractions reveals a distinct set of polypeptides associated with secretory vesicles.     

Preparation of Secretory Vesicle-Free Plasma Membranes by Isopycnic Sucrose Gradient Fractionation of Neutrophils Purified by the Gelatin Method

Isolated human neutrophils serve as a model for the in vitro study of host defensive processes as well as the cell biology and biochemistry of primary human cells. We demonstrate that the requirements of the gelatinbased procedure for neutrophil isolation from whole blood induces the complete loss of secretory vesicles from in vitro isolated populations, whereas isolation by a dextran-based methodology results in the preservation of this organelle. Following density fractionation of cellular cavitates, examination of commonly employed plasma membrane marker activities yielded subcellular localization patterns that were indistinguishable between dextran- or gelatin-isolated populations, indicating both populations to be otherwise comparable in terms of the relative complexity and large-scale organization of plasma membranes. Given that the cell surface upregulation of secretory vesicles is implicated as an initial requirement of neutrophil activation as well as an intrinsic feature of neutrophil priming, we show that dextran and gelatin-isolated neutrophils may be considered to occupy functionally nonactivated and primed cellular states, respectively. These differences in phenotype can be exploited in specific ways. We suggest that the gelatin method has technical advantages with regard to the study of neutrophil plasma membranes. In particular, results from this study indicate the gelatin method to be a reliable and effective preparatory technique appropriate for tandem use with density fractionation procedures to achieve rapid isolation of plasma membranes that are uncontaminated by secretory organelles.     

Myosin Va transports dense core secretory vesicles in pancreatic MIN6 beta-cells

The role of unconventional myosins in neuroendocrine cells is not fully understood, with involvement suggested in the movement of both secretory vesicles and mitochondria. Here, we demonstrate colocalization of myosin Va (MyoVa) with insulin in pancreatic beta-cells and show that MyoVa copurifies with insulin in density gradients and with the vesicle marker phogrin-enhanced green fluorescent protein upon fluorescence-activated sorting of vesicles. By contrast, MyoVa immunoreactivity was poorly colocalized with mitochondrial or other markers. Demonstrating an important role for MyoVa in the recruitment of secretory vesicles to the cell surface, a reduction of MyoVa protein levels achieved by RNA interference caused a significant decrease in glucose- or depolarization-stimulated insulin secretion. Similarly, expression of the dominant-negative-acting globular tail domain of MyoVa decreased by approximately 50% the number of vesicles docked at the plasma membrane and by 87% the number of depolarization-stimulated exocytotic events detected by total internal reflection fluorescence microscopy. We conclude that MyoVa-driven movements of vesicles along the cortical actin network are essential for the terminal stages of regulated exocytosis in beta-cells.     

Studies on proinsulin and proglucagon biosynthesis and conversion at the subcellular level: I. Fractionation procedure and characterization of the subcellular fractions

Anglerfish islets were homogenized in 0.25 M sucrose and separated into seven separate subcellular fractions by differential and discontinuous density gradient centrifugation. The objective was to isolate microsomes and secretory granules in a highly purified state. The fractions were characterized by electron microscopy and chemical analyses. Each fraction was assayed for its content of protein, RNA, DNA, immunoreactive insulin (IRI), and immunoreactive glucagon (IRG). Ultrastructural examination showed that two of the seven subcellular fractions contain primarily mitochondria, and that two others consist almost exclusively of secretory granules. A fifth fraction contains rough and smooth microsomal vesicles. The remaining two fractions are the cell supernate and the nuclei and cell debris. The content of DNA and RNA in all fractions is consistent with the observed ultrastructure. More than 82 percent of the total cellular IRI and 89(percent) of the total cellular IRG are found in the fractions of secretory granules. The combined fractions of secretory granules and microsomes consistently yield >93 percent of the total IRG. These results indicate that the fractionation procedure employed yields fractions of microsomes and secretory granules that contain nearly all the immunoassayable insulin and glucagons found in whole islet tissue. These fractions are thus considered suitable for study of proinsulin and proglucagon biosynthesis and their metabolic conversion at the subcellular level.     

A fine-structural analysis of mouse molar odontoblast maturation.

The first mandibular molars of the Swiss albino mice, 1 through 4 days of age, were fixed in glutaraldehyde or Karnovsky's fixative. The tissues were postfixed in OSO4, dehydrated and embedded in Epon. The prepolarizing, polarizing and secretory odontoblasts were described. The prepolarizing cells, located in the vicinity of the cervical loop, were mesenchymal-like in morphology. The cells of the polarizing stage possessed organelles indicative of protein synthesis. The nucleus was located proximally. Aperiodic fibers were evident in the wide basement membrane. The secretory odontoblasts were long, slender, polarized cells closely adjoining one another. Each odontoblast possessed six morphologically discernible regions: (1) an infranuclear region, limited in size and containing few cellular organelles; (2) a nuclear region, housing the oval nucleus and a few associated lamellae of rough endoplasmic reticulum as well as a limited number of mitochondria; (3) a supranuclear rough endoplasmic reticulum region, possessing an abundance of these organelles as well as some mitochondria and secretory vesicles; (4) a Golgi region, occupying the middle third of the cell, housing the elements of an extensive Golgi apparatus which was surrounded by peripherally located profiles of rough endoplasmic reticulum; additionally, this region contained smooth endoplasmic reticulum, mitochondria, numerous secretory granules and vesicles and occasional intracellular collagen fibers; (5) an apical rough endoplasmic reticulum region, containing a rough endoplasmic reticulum component that was less extensive than its supranuclear counterpart; in addition, this region was the one richest in mitochondria and contained a plethora of secretory vesicles and granules; (6) the odontoblastic process, a region mostly void of organelles, containing various secretory products, some of which appeared to be in the process of being released extracellularly into the surrounding dentin matrix.     

Secretory organelles in ECL cells of the rat stomach: an immunohistochemical and electron-microscopic study

ECL cells are numerous in the rat stomach. They produce and store histamine and chromogranin-A (CGA)-derived peptides such as pancreastatin and respond to gastrin with secretion of these products. Numerous electron-lucent vesicles of varying size and a few small, dense-cored granules are found in the cytoplasm. Using confocal and electron microscopy, we examined these organelles and their metamorphosis as they underwent intracellular transport from the Golgi area to the cell periphery. ECL-cell histamine was found to occur in both cytosol and secretory vesicles. Histidine decarboxylase, the histamine-forming enzyme, was in the cytosol, while pancreastatin (and possibly other peptide products) was confined to the dense cores of granules and secretory vesicles. Dense-cored granules and small, clear microvesicles were more numerous in the Golgi area than in the docking zone, i.e. close to the plasma membrane. Secretory vesicles were numerous in both Golgi area and docking zone, where they were sometimes seen to be attached to the plasma membrane. Upon acute gastrin stimulation, histamine was mobilized and the compartment size (volume density) of secretory vesicles in the docking zone was decreased, while the compartment size of microvesicles was increased. Based on these findings, we propose the following life cycle of secretory organelles in ECL cells: small, electron-lucent microvesicles (pro-granules) bud off the trans Golgi network, carrying proteins and secretory peptide precursors (such as CGA and an anticipated prohormone). They are transformed into dense-cored granules (approximate profile diameter 100 nm) while still in the trans Golgi area. Pro-granules and granules accumulate histamine, which leads to their metamorphosis into dense-cored secretory vesicles. In the Golgi area the secretory vesicles have an approximate profile diameter of 150 nm. By the time they reach their destination in the docking zone, their profile diameter is between 200 and 500 nm. Exocytosis is coupled with endocytosis (membrane retrieval), and microvesicles in the docking zone are likely to represent membrane retrieval vesicles (endocytotic vesicles).     

Serous cutaneous glands in the South American horned frog Ceratophrys ornata (Leptodactylformes, Chthonobatrachia, Ceratophrydae): ultrastructural expression of poison biosynthesis and maturation

Serous cutaneous glands are described in newly metamorphosed and juvenile specimens of the horned frog Ceratophrys ornata using light and transmission electron microscopy. We report patterns of biosynthesis and maturation of the specific product of the gland secretory unit. The syncytial, secretory compartment possesses a complex of endoplasmic reticulum (predominantly smooth endoplasmic reticulum after metamorphosis) and Golgi stacks. The serous product is weak in density and is contained in vesicles involved in repeating merging processes. During this maturation activity, secondary lysosomes are observed, which derive from autophagic processes (crinophagy) involving the secretory materials. Ceratophrys ornata, a species representative of the type genus of the family Ceratophrydae, belongs to the heterogeneous group of anurans that, possibly as the result of convergence, all produce cutaneous poisons consisting of vesicles or faint density granules.     

生姜根茎的发育过程及分泌腔的超微结构

为了解生姜(Zingiber officinale Roscoe)根茎的发育过程,在光学显微镜和电子显微镜下对不同发育时期的生姜进行显微和超微结构观察,并对分泌腔的发生发育过程进行了研究。结果表明,幼嫩期的生姜,表皮以内的基本组织可大致分为皮层、拟内皮层和中柱。次生加厚分生组织起源于中柱外侧一些细胞,细胞分裂和体积增大促使生姜发育。薄壁细胞内有大量的淀粉粒且其数量、形状和大小因发育时期而不同。分泌腔广布于生姜中,其发育过程可分为3个阶段:分泌腔原始细胞团形成、分泌腔的发生和成熟分泌腔形成。生姜精油主要在线粒体、质体和细胞质中合成。本研究为生姜药用资源的开发利用提供了理论依据。