Ultrastructure of dormant buds of Salix sp. in early winter

In the apex of dormant buds of Salk a histological zonation comparable to that found in growing buds was observed. However, significant changes in relative volumes of cell components between dormant and growing buds were noted; the dormant buds had a lower volume density of vacuoles and higher relative volumes of mitochondria, plastids, lipid bodies, and starch grains than the growing buds. In the leaf primordia the relative volume of nuclei decreased with age, while the relative volume of plastids and mitochondria increased. The large central vacuole found in cells of e.g. the pro-cambium and rib meristem in growing buds is split into many smaller ones during the winter. A high content of tannin and calcium oxalate crystals was noted in dormant buds. They also accumulate lipids and starch. Phytoferritin may appear in plastids. Stacked ER and concentric sheaths of ER around lipid bodies appear, probably as a consequence of either anaerobic conditions or water stress. Several indications of metabolic activities in the seemingly dormant buds were found; plasmatubules at the plasmalemma particularly in the procambium, sheaths of smooth ER around the plastids, electron opaque globules (probably calcium-binding sites), and vacuoles that seemed to be autophagic.     

Differences in the volume distributions of human lung mast cell granules and lipid bodies: evidence that the size of these organelles is regulated by distinct mechanisms

We analyzed transmission electron micrographs of human lung mast cells by digitized planimetry and point counting to determine the cross-sectional areas of two distinct cytoplasmic organelles: specific granules and lipid bodies. Specific granules have a limiting membrane and often contain one or more cylindrical scroll-like inclusions. By contrast, lipid bodies are on average much larger than granules and lack both limiting membranes and inclusions. The measured cross-sectional areas of lipid bodies and scroll-containing granules were converted to equivalent volumes, and the noise in the frequency distribution of these volumes was smoothed using a moving bin technique. This analysis revealed (a) a periodic, multimodal distribution of granule equivalent volumes in which the modes fell at volumes that were integral multiples of the volume defined by the first mode (the "unit volume"), and (b) a modal granule equivalent volume frequency that occurred at a magnitude equal to four "unit volumes." Thus, specific granules appear to be composed of units of a narrowly fixed volume. Furthermore, the mean volume of intragranule inclusions was 0.0061 mu3, a value very similar to that calculated for the "unit volume" (0.0071 mu3). This result suggests that each "unit volume" comprising the individual scroll-type granules contains (or is capable of generating or accommodating) a single scroll-like inclusion. In contrast to the specific granules, mast cell lipid bodies lack a periodic, multimodal volume distribution. Taken together, these findings suggest that the volumes of human lung mast cell granules and lipid bodies are regulated by distinct mechanisms.     

Quantitative analysis of the structural events associated with antidiuretic hormone-induced volume reabsorption in the rabbit cortical collecting tubule

Summary We quantitatively examined the influence of antidiuretic hormone (ADH)-dependent volume reabsorption on the morphology of the rabbit cortical collecting tubule. Estimates of cell volume and the geometry of the lateral intercellular spaces were extracted from differential interference contrast images of perfused nephron segments using the morphometric procedures described in the preceding paper (K.L. Kirk, D.R. DiBona and J.A. Schafer,J. Membrane Biol. 79:53–64, 1984). The results indicate that ADH addition in the presence, but not absence, of a lumen-to-bath osmotic gradient (130 to 290 mOsm) stimulated transepithelial volume flow and simultaneously increased the volumes of both the cells (+28%) and the lateral intercellular spaces (+78%). In addition, the formation of cytoplasmic vacuoles could be observed during the latter stages of the swelling response, and vacuole formation continued well after new steadystate values for transepithelial water flow and cell volume had been reached. Two main conclusions can be drawn from these results. First, the cytoplasmic vacuoles comprise a slowly filling compartment that lies in parallel to the transepithelial pathway for ADH-stimulated volume reabsorption. Second, from the magnitude of the cell volume increase, we estimate that the hydraulic conductivities of the opposing cell membranes are nearly equal during maximal ADH stimulation.     

Vacuolation: Origin and development of the lysosomal apparatus in root-tip cells

Summary The morphology of vacuolation has been investigated in root tip cells of corn using the freeze-etching technique. The genesis of vacuoles involves the following processes: a) Formation of small, endoplasmic-reticulum (ER)-derived vesicles (provacuoles); b) fusion of provacuoles resulting in the formation of small vacuoles, and followed by fusion and expansion of vacuoles; c) incorporation of large, dictyosome-derived vesicles into vacuoles by invagination of the tonoplast; d) invagination of the tonoplast resulting in the incorporation of cytoplasmic material into vacuoles. The morphological findings are correlated with biochemical data obtained from isolated vacuoles (lysosomes). Provacuoles (ER-derived vesicles) are shown to be primary lysosomes; their hydrolases arise from the ER. Vacuoles represent secondary lysosomes (digestive vacuoles) of the higher-plant cell. The metabolic role of lytic processes proceeding in the lysosomal apparatus is discussed.     

Analysis of number, size and distribution patterns of lipid vacuoles in benign and malignant mesothelial cells

A quantitative analysis of the lipid vacuoles in benign hypertrophic and neoplastic mesothelial cells, using a size-independent distribution index, showed that computer-assisted image analysis for distribution patterns of cytoplasmic components can aid in distinguishing benign from malignant cells. Benign mesothelial cells had fewer lipid vacuoles, which were smaller and predominantly found around the nuclei. It is argued that, due to the high surface tension in the lipid vacuoles, the largest vacuoles are found in the center of the cells, which is the least flattened part of the air-dried mesothelial cells. It seems likely that the distribution pattern of rigid substructures, such as lipid vacuoles, varies between histologic and cytologic material as well as between cells processed by different cytologic methods with various cell-flattening artifacts. The study of the distribution of cytoplasmic components that differ in size was enhanced by using the defined size-independent distribution index, which incorporates the radius of the cell, the radius of the vacuoles and their respective centers of gravity.     

An Analysis of Ultrastructural Changes during Oosphere-initial Development in Oogonia from Ca2+-sufficient and Ca2+-deficient cultures of Saprolegnia terrestris Cookson ex Seymour

The central vacuole system of oogonia of Saprolegnia terrestrisfrom Ca²⁺-sufficient cultures was fully enlarged prior to theformation of oosphere initials, which did not involve cleavagevesicles. In oogonia with fully-enlarged central vacuole systems,subsidiary vacuoles at the periphery of the system sometimescontained dense bodies, and dense-body profiles were sometimespresent within sections of the central vacuole system itself.As the central vacuole system enlarged, volume densities ofdense-body vesicles, peripheral vacuoles, lipid bodies and thecytoplasmic matrix decreased relative to total oogonial volume(peripheral protoplasm volume plus central vacuole volume),while the volume density of nuclei increased and that of mitochondriaremained constant. Relative to the peripheral protoplasm only,volume densities of dense-body vesicles, lipid bodies and mitochondriaincreased and volume densities of peripheral vacuoles and ofthe cytoplasmic matrix decreased, while the volume density ofnuclei increased during central vacuole enlargement but subsequentlydecreased during formation of oosphere initials. Under conditionsof Ca²⁺ deficiency, the volume densities of mitochondria andof the cytoplasmic matrix were significantly increased, whilethat of lipid bodies was significantly decreased, at early stagesof oogonial development; the volume densities of other organelleswere not significantly altered at any stage. Saprolegnia terrestris, oogonia, development, calcium, ultrastructure, stereology     

马占相思子叶离体培养中细胞早期变化的研究

用光学和电子显微镜观察马占相思子叶在离体培养中的细胞早期变化,结果表明,未培养的子叶薄壁细胞内充满大量贮藏物质,在脱分化过程中,贮藏物质逐渐减少,细胞核体积增大,液泡蛋白体出现,质体转化为原质体,线粒体,内质网等细胞器数量增加,马脱分化启动后的细胞分裂方式进行了讨论。     

Influence of a short light pulse at night on the ultrastructure of the rat pinealocyte: a quantitative study

Summary Although it is generally known that light strongly influences N-acetyltransferase activity and melatonin production in the pineal gland, little information is available concerning morphological changes following light exposure. As exposure of rats to a short light pulse at night rapidly depresses melatonin synthesis, we decided to determine whether this experimental condition produces rapid changes in the pinealocyte organelles. A 30-min light pulse at night (six hours after lights out) provoked rapid changes in the relative volumes of some pinealocyte organelles. The volume fractions of mitochondria, Golgi apparatus and lipid droplets, and the numbers of dense-core vesicles and synaptic ribbons decreased, whereas the volume fraction of lysosomes increased. There were no differences in the volumes of granular endoplasmic reticulum and vacuoles containing flocculent material in those animals exposed to light compared with control animals. These results indicate that a short light pulse at night causes ultrastructural changes that can be interpreted as morphological features of diminished activity of pinealocytes.     

Electron microscopy study of deoxyribonuclease penetration into chick embryo fibroblasts and the effect of the enzyme on the cells

Peroxidase labeled DNase (0.25 g/ml) penetrated into the chick fibroblast culture cells by means of pinocytosis to be localized in pinocytotic vacuoles. Within a 24 hour-incubation of the cell culture with DNase a relative volume of vacuoles in cells increased from 4.6 to 19.5 per cent, the majority of pinocytic vacuoles being filled with labeled DNase. The incubation of cells with non-labeled DNase (24 hours) did not damage DNA-containing cell structures. The data obtained permit to explain the selective effect of the enzyme on the viral DNA and the inhibition of reproduction of DNA-containing viruses by the interaction of the viral DNA and DNase inside pinocytic vacuoles which protect the cells from the enzyme damaging effect.     

A seasonal change in blood cell volume of the Rottnest Island Quokka, Setonix brachyurus

Comparison of the red cell and plasma volumes (T-1824) of wild Quokkas captured in spring (October) with volumes of animals captured in autumn (May) showed that no seasonal change in average plasma volume occurred but a 42% average decrease in red cell volume did occur in autumn. Control animals kept in compounds showed no seasonal change in either average plasma or red cell volume. The available evidence suggests that the seasonal decline in red cell volume results from the semi-starvation suffered by the wild population during the late summer and autumn of each year. The average relative red cell, plasma and whole blood volumes of well-fed Quokkas captured in October were 24.6±3.1; 37.0±3.0; and 61.7±4.5 ml/kg, and equivalent measures of domesticated Quokkas were 28.0±3.2; 40.5±2.8; and 68.5±5.3 ml/kg. These values lie within the ranges of comparaable blood compartment volumes of eutherian mammal species.     

银杏套细胞发育的解剖学研究

银杏套细胞起源于近雄配子体表达的颈卵器母细胞周围细胞,中央细胞形成时,套细胞呈明显的一层,围绕颈卵器紧密排列,随着颈卵器的发育,套细胞体积逐渐地大,细胞质变浓厚,细胞质中脂滴增多,套细胞和中央细胞的接触壁开始出现局部加厚,在颈卵器发育的泡沫化阶段,套细胞和中央细胞的接触壁不均匀加厚较为显著,在较薄的区域可见胞间连丝,受精前,套细胞中液泡增多,脂滴迅速减少,造淀粉体增大,套细胞与卵细胞的接触壁的不均匀加厚非常明显,精核进入颈卵器以后,卵细胞与套细胞的接触壁和卵细胞的质膜之间形成一个薄厚不均的间隔层,受精卵分裂时,受精卵细胞与套细胞接触壁的凹陷处可见许多小泡和内质网,游离核期时,套细胞内出现大量小液泡,细胞内含物迅速消失,套细胞外形变长,胚胎长出颈卵器后,套细胞逐渐解体消失。     

Ulfrastructure of the histological zones in growing vegetative buds of Salix spp.

Ultrastructural differentiation in the shoot apex of growing vegetative buds of Salix was studied, and some micrographs analysed morphometrically. The distribution of inorganic phospahte (P;) was analysed cytochemically. A distinct histological zona–tion was observed in the apex. The relative volumes of nuclei and plastids were significantly higher in the central tunica zone than in the peripheral one. The corpus differed from the central tunica zone by significantly lower volume density of nuclei and higher of vacuoles and mitochondria. During differentiation of the rib meristem vacuole volume increased significantly, while the relative volumes of nuclei, mitochondria, nucleoli, and heterochromatin decreased. It was not possible to decide whether the vacuoles originate from ER or GERL. Morphogenesis of chloroplasts with large starch grains and grana from proplastids was evident in the rib meristem; dedifferentiation to S–plastids was found in the protophloem. Prolamellar bodies were observed in the procambium plastids. The protophloem was characterized by P–protein and spiny vesicles. P_i was found in the nucleoli of most epidermis cells, several procambium cells, and a few chlorencyma cells, but never in the tunica of the growing apical and developing lateral buds. P_i also occurred in some plasmalemma–somes and occasionally in the walls in connection with plasmodesmata.     

The effect of oligomycin and cycloheximide on the ultrastructure of the segregation apparatus and on protein synthesis in the erythrocytes of the common frog

The incubation of frog erythrocytes in the Ringer solution with novocaine (4.6 x 10(-3) M) during 24 hours at 10 degrees C provoked vacuole formation (segregation zones). Changes of the novocaine solution for a fresh Ringer solution and the following 48 hour incubation was accompanied by a decrease in the number of vacuoles both electron-translucent and containing membranous material. Simultaneously, the number of vacuoles with amorphous material only and with amorphous and membranous substances was seen to increase. Under the action of cycloheximide (1.10(-2) M) or oligomycin (2.5 x 10(-6) M) on erythrocytes with preformed vacuoles for 48 hours the total number of vacuoles and their dimensions decreased, with numerous amorphous inclusions appearing. Vacuoles with amorphous and membranous material increased in size. Similar ultrastructural changes in the segregation zones under the influence of both the inhibitors were observed showing the appearance of thick threads and a decreased share of electron-translucent vacuoles. A specific effect of cycloheximide, compared to that of oligomycin, involved the expansion of smooth endoplasmic reticulum cisternae. Under the influence of novocaine, 3H-leucin incorporation in proteins of frog erythrocytes was intensified. However, this incorporation was considerably inhibited by cycloheximide. Erythrocytes with segregation zones were more inhibitor susceptible than erythrocytes without vacuoles. The inhibitory effect was stronger early after their administration to the incubation medium, compared to the later periods.     

Infection of Vero cells with Coxiella burnetii phase II: relative intracellular bacterial load and distribution estimated by confocal laser scanning microscopy and morphometry

Coxiella burnetii, the agent of Q fever in man and of coxiellosis in other species, is an intracellular pathogen not yet grown axenically. Confocal laser fluorescence microscopy and morphometry were used to measure relative C. burnetii phase II loads and their intracellular distribution in aldehyde fixed and DAPI stained Vero cell monolayers. The fluorescence of single horizontal optical sections provided useful information on relative loads of bacteria in cells and vacuoles. The relative density of the bacteria in the vacuoles was inferred from ratios of fluorescence to vacuolar section areas. Relative bacterial loads, bacterial densities and section areas of large vacuoles increased exponentially between days 2 and 4 of the infection of gamma-irradiated host cells, stabilized between days 4 and 6, and decreased thereafter. Estimated minimum doubling times were higher for the overall complement of the intracellular organisms (about 12 h) than for bacteria that were confined to larger vacuoles (about 10 h).     

Blood volume measurement in baboons: simultaneous estimation of red cell volume and plasma volume

A method is described for frequent sequential blood volume estimation in baboons using 32P for red cell volume measurements and 125I-albumin for simultaneous plasma volume measurements. Values for red cell, plasma, and total blood volumes are reported. Close correlations of the volumes to bodyweight were demonstrated. Circulatory half-lives of the isotopes, determined from disappearance curves, confirmed their suitability for serial measurements in these baboons.     

豌豆根瘤脂质体的分布及形态特征

豌豆根瘤中有大量的脂质体,广泛分布于非侵染细胞和侵染细胞内,它既可以存在细胞质中,也可位于液泡里面。有时单个存在,有时又多个聚集在一起。非侵染细胞与侵染细胞相比,前者中的脂质体明显多于后者。这些脂质体近似圆形或椭圆形,表面无膜,电子密度较高,内部无固定的结构,常有一些细胞器位于它的附近。讨论了脂质体的细胞发育及细胞种类的关系。     

Morphometric study of Lemna gibba in relation to the use of compartmental analysis and the flux-ratio equation in higher plant cells

Morphometric characteristics of Lemna gibba L. cells have been estimated. The mean relative volumes of the wall, of the cytoplasm and of the vacuoles were 0.03, 0.32 and 0.65, respectively. The distribution of the individual values has been studied: for instance 29% of the cells had a mean relative volume of the vacuoles close to 0.73, 39% to 0.68, 19% to 0.61 and 13% to 0.51. The mean value and distribution of the surface areas of the tonoplast and plasmalemma were also determined. This allows us to discuss the active or passive character of the transport of various substances at the plasmalemma and at the tonoplast, according to the usual flux-ratio approach. The feasibility of such an approach in ordinary (non-giant) living cells is discussed with regard to the degree of reliability of the measurements which can be performed with such cells.     

Electron microscopic observations on the involution of the human corpus luteum of menstruation

Summary The involution of the granulosa lutein cell in the human corpus luteum is characterized by a dilatation of agranular endoplasmic reticulum vesicles and tubules. This process continues until the whole cell is filled with large vacuoles and the cytoplasm is reduced to thin strands between the vacuoles. The contents of the latter are of low electron density in contrast to the very electron dense lipid droplets in vascularization, bloom and early involution phase. Light microscopical evidence shows that the contents of the vacuoles must be lipid and the lower electron density might be explained by the relative decrease in phospholipids and increase in cholesterol and cholesterol esters during involution. Simultaneously processes of focal cytoplasmic degradation resulting in autophagic vacuoles occur in the cells. These lead in some cases to the formation of residual bodies which can be identified with lipofuscin granules. Finally, the degenerating cells disintegrate and part of the debris, including the lipofuscin granules are phagocytosed by macrophages, the so-called fluorocytes of Hamperl. During involution an amorphous substance with some protofilaments and collagen fibrils is deposited in the spaces between the shrinking lutein cells. This is the fibrohyalin material which will form the bulk of the corpus albicans.We are grateful for the assistance given by Dr. J. M. Moyes of the Women's Hospital, Crown Street, Sydney and the staff of King George V. Hospital at Sydney with the supply of the material.     

Changes in the lipid inclusion/Sertoli cell cytoplasm area ratio during the cycle of the human seminiferous epithelium

The area occupied by Sertoli cell lipid inclusions--electron-lucent lipid vacuoles (LLV) and electron-dense lipid droplets (DLD)--at each stage of the cycle of the seminiferous epithelium was measured on electron micrographs in young adults and elderly men, and expressed as the ratio "area occupied by lipid inclusions/area occupied by the Sertoli cell cytoplasm". For LLV this ratio increased from stage I to stage III, and decreased from stage IV to stage VI in young adults. These results suggest that the development of LLV is synchronized with the spermatogenic process: the residual bodies released in stages I and II are phagocytized by Sertoli cells and transformed into LLV; the amounts of LLV decrease in the subsequent stages of the cycle and increase again when new residual bodies appear. In elderly men the ratio LLV/Sertoli cell cytoplasm was 1.9-2.9 times higher than in young adults at each stage of the cycle. This increase may be related to the increased germ-cell degeneration observed in ageing testes, DLD were less abundant than LLV and the DLD/Sertoli cell cytoplasm ratio did not undergo cyclic changes in young adults or elderly men.     

Ultrastructural distribution of morphology of the mammary gland with observations on the size fat droplets in milk of the Weddell seal Leptonychotes weddelli (Pinnipedia)

Ultrastructural observations were made of the non-lactating and lactating mammary gland of the Weddell seal, and measurements of several cell components were compared with those in other species to determine whether there are any morphological modifications within the gland to explain the unusual milk composition and very rapid growth of sucking young in this species.
The mammary parenchyma in non-lactating and lactating Weddell seals is almost identical morphologically to that found in other mammals. Although the relative volumes of most organelles are similar to those in other eutherians, the relative volume of rough endoplasmic reticulum (RER) is reduced in the Weddell seal. In addition, the absolute and relative volumes of Golgi vacuoles are smaller in the Weddell seal, probably associated with the low lactose and water content of the milk. The synthesis and secretion of milkspecific proteins and fat droplets by mammary secretory cells in the Weddell seal appear to be identical to other eutherians. Relatively small numbers of fat droplets less than 1 μm diameter are present in epithelial cells, alveolar lumina and milk samples, and there is a far greater contribution by large fat droplets to the total fat volume of Weddell seal milk than milk from other mammals.