The subcellular organization of stomatal initials in sugarcane leaves: the guard and subsidiary mother cells

1977 ◽  
Vol 55 (22) ◽  
pp. 2801-2809 ◽  
Author(s):  
A. P. Singh
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Close Association ◽  
Preprophase Band ◽  
Central Position ◽  
Guard Mother Cell ◽  
Subcellular Organization ◽  
Guard Mother Cells ◽  
Mother Cells ◽  
Preprophase Bands

The subcellular organization of guard and subsidiary mother cells in sugarcane leaves was examined by electron microscopy. Guard and subsidiary mother cells assume a characteristic shape before mitosis and contain variable numbers of mitochondria, proplastids, dictyosomes, and cisternae of rough endoplasmic reticulum. In guard mother cells, the nucleus occupies a central position, whereas in subsidiary mother cells, the nucleus is located toward one end of the cell, near the guard mother cell. Microtubules are found in both guard and subsidiary mother cells and are either closely grouped to form defined preprophase bands or randomly dispersed between the nucleus and the preprophase bands. Many of the dispersed microtubules occur in close association with the nucleus in both guard and subsidiary mother cells. Possible functions for these preprophase microtubules are discussed in relation to their organization in the preprophase band, their orientation, and their distribution within guard and subsidiary mother cells.

Extrusion of Nuclear Material During Oogenesis in Blatta Orientalis

1962 ◽  
Vol s3-103 (62) ◽  
pp. 141-145
Author(s):  
R.A. R. GRESSON ◽  
L. T. THREADGOLD
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Close Association ◽  
Nuclear Material ◽  
Blatta Orientalis ◽  
Nucleolar Material

That nucleolar material is extruded to the cytoplasm of the young oocyte of Blatta orientalis is confirmed by means of electron microscopy. The nucleolus and nucleolar extrusions are shown to contain RNA. In addition to the nucleolar extrusions, vesicle-like structures originate in the nuclear membrane and from there pass into the cytoplasm where they become indistinguishable from elements of the endoplasmic reticulum. When the nucleolar extrusions reach the cytoplasm they increase in size, come into close association with a few mitochondria, and migrate towards the periphery of the cell. It is concluded that the emission of material from the nucleolus and the passage of vesicles from the nuclear membrane to the cytoplasm are necessary prerequisites for the process of vitellogenesis.

Cytological studies on physodes in the vegetative cells of Cystoseira stricta Sauvageau (Phaeophyta, Fucales)

1980 ◽  
Vol 41 (1) ◽  
pp. 209-231
Author(s):  
L. Pellegrini
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Cell Walls ◽  
Higher Plants ◽  
Close Association ◽  
Chloroplast Envelope ◽  
Osmiophilic Granules ◽  
Cytological Changes ◽  
Ultrastructural Characteristics ◽  
Secondary Lysosomes

Physodes have been recognized in meristodermic and promeristematic cells by correlated light- and electron-microscope investigations using different fixation procedures. They are vesicles which contain an osmiophilic material of phenolic nature. Their content changes in appearence according to the fixative used. Osmiophilic deposits are often associated with coiled and disturbed lamellar formations. It has been possible to distinguish several ultrastructural stages which occur during the secretion of the content of the physodes, namely: a chloroplast accumulation and exudation, and a reticular transport to accumulation vacuoles where materials undergo evolution or hydrolysis. Inside plastids, osmiophilic granules are found in close association with thylakoid stacks. They may contain the polyphenolic precursors of physodes, though this has not yet been proved by electron-microscopy procedures. They are expelled from plastids to the chloroplast endoplasmic reticulum. The mechanism of transfer through the chloroplast envelope endoplasmic reticulum. The mechanism of transfer through the chloroplast envelope remains to be elucidated. Lytic activities have been reported inside physodes which might thus act in the same way as the secondary lysosomes of animals and higher plants. Occasionally, the physode content seems to be excreted from the cytoplasm to the cell walls by exocytosis after the probable fusion of plasmalemma and tonoplast. These cytological changes, observed in the vegetative apex of a brown alga, recall some ultrastructural characteristics of the secretory processes described in various glandular tissues of higher plants and which consist of the synthesis, the transport and the elimination of an exudate of flavonic, terpenic or lipophenolic nature.

A comparative light and electron microscopic study of microspore and tapetal development in male fertile and cytoplasmic male sterile oilseed rape (Brassica napus)

1986 ◽  
Vol 64 (5) ◽  
pp. 1055-1068 ◽  
Author(s):  
I. Grant ◽  
W. D. Beversdorf ◽  
R. L. Peterson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Brassica Napus ◽  
Microspore Development ◽  
Male Sterile ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Mother Cells ◽  
Scanning Electron

The cytological development of male cells and the tapetum of male fertile and combined cytoplasmic triazine-resistant cyto-plasmic-genetic male sterile (ctr) lines of B. napus L. was studied using light, scanning electron, and transmission electron microscopy. Development of the cytoplasmic-genetic male sterile anther was similar to the normal anther up to and including meiotic prophase I. After this stage, degeneration of the microspore mother cells occurs within the callose walls, and tetrads of microspores are not formed. These degenerating microspore mother cells appear to develop numerous endoplasmic reticulum derived vesiculated structures, which may be involved in lysis of organelles. Degeneration occurs simultaneously with a proliferation of the tapetum, which eventually fills the anther locule. It is not clear whether the abortion of the microspore mother cells during meiosis stimulates proliferation of the tapetum or whether the proliferating tapetum actually interferes with microspore development thereby causing degeneration. Dilated endoplasmic reticulum cisternae containing crystalline-like deposits, and plastids with osmiophilic bodies, are frequent in cells of the proliferated tapetum of cytoplasmic-genetic male sterile anthers.

The origin and fate of the nuclear membrane in meiosis

1960 ◽  
Vol 152 (948) ◽  
pp. 353-366 ◽  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Phase Contrast ◽  
Close Association ◽  
Early Prophase ◽  
Daughter Cells ◽  
Nuclear Membranes ◽  
Contrast Microscopy ◽  
Surrounding Membrane

The behaviour of the nuclear membrane during meiotic division in locust spermatocytes has been studied by electron microscopy. Preliminary observations were made on living cells from locusts, grasshoppers and beetles by phase-contrast microscopy and on snail and newt spermatocytes by electron microscopy. The mitochondria come into close association with the nuclear membrane during prophase and are often clustered round regions of degenerating nuclear membrane. The mitochondrial membranes sometimes appear to be fused with the nuclear membrane, and gaps in the latter are often found near mitochondria. Lamellar stacks are found in the cytoplasm during early prophase and closely resemble the nuclear membrane in the same cells ; they are generally annulate in spermatogonia and primary spermatocytes butsmooth-walled in secondary spermatocytes. There is evidence that the stacks arise by repeated folding of the nuclear membrane and become converted into endoplasmic reticulum. After division, the daughter cell chromosomes are at first devoid of a surrounding membrane. Elements of the endoplasmic reticulum accumulate between the mitochondria and gradually surround the chromosomes. These elements fuse to form a continuous double nuclear membrane. It is suggested that the nuclear membrane, endoplasmic reticulum and cell membrane are composed of the same material, which can be transformed into different structures according to the needs of the cell. The nuclear membrane is converted into endoplasmic reticulum during division and stored in the cytoplasm . The new nuclear membranes in the daughter cells are formed by the fusion of elements of the endoplasmic reticulum.

Modification of Pineal Ultrastructure by Exogenous Hormones

1967 ◽  
Vol 25 ◽  
pp. 170-171
Author(s):  
R. A. Turner ◽  
A. E. Rodin ◽  
D. K. Roberts
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Estradiol Benzoate ◽  
Female Rats ◽  
List Type ◽  
Type Number ◽  
Pregnant Rats ◽  
Gonadal Atrophy ◽  
Pineal Ultrastructure

There have been many reports which establish a relationship between the pineal and sexual structures, including gonadal hypertrophy after pinealectomy, and gonadal atrophy after injection of pineal homogenates or of melatonin. In order to further delineate this relationship the pineals from 5 groups of female rats were studied by electron microscopy:ControlsPregnant ratsAfter 4 weekly injections of 0.1 mg. estradiol benzoate.After 8 daily injections of 150 mcgm. melatonin (pineal hormone).After 8 daily injections of 3 mg. serotonin (melatonin precursor).No ultrastructural differences were evident between the control, and the pregnancy and melatonin groups. However, the estradiol injected animals exhibited a marked increase in the amount and size of rough endoplasmic reticulum within the pineal cells.

Copper Localization in Cirrhotic Rat Liver by Scanning Electron Microscopy

1969 ◽  
Vol 27 ◽  
pp. 38-39 ◽  
Author(s):  
J. C. Russ ◽  
E. McNatt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Copper Acetate ◽  
Lead Citrate ◽  
Dense Bodies ◽  
Transmission Electron ◽  
Electron Mode ◽  
Scanning Electron

In order to study the retention of copper in cirrhotic liver, rats were made cirrhotic by carbon tetrachloride inhalation twice weekly for three months and fed 0.2% copper acetate ad libidum in drinking water for one month. The liver tissue was fixed in osmium, sectioned approximately 2000 Å thick, and stained with lead citrate. The section was examined in a scanning electron microscope (JEOLCO JSM-2) in the transmission electron mode.Figure 1 shows a typical area that includes a red blood cell in a sinusoid, a disse, and a portion of the cytoplasm of a hepatocyte which contains several mitochondria, peribiliary dense bodies, glycogen granules, and endoplasmic reticulum.

Morphological and biochemical analyses of changes in rat hepatocytes related to wine and ethanol consumption

1984 ◽  
Vol 42 ◽  
pp. 232-233
Author(s):  
S.M. Geyer ◽  
C.L. Mendenhall ◽  
J.T. Hung ◽  
E.L. Cardell ◽  
R.L. Drake ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Malic Enzyme ◽  
Smooth Endoplasmic Reticulum ◽  
Rat Hepatocytes ◽  
Mature Male ◽  
Treatment Groups ◽  
Malic Enzyme Activity ◽  
Biochemical Analyses

Thirty-three mature male Holtzman rats were randomly placed in 3 treatment groups: Controls (C); Ethanolics (E); and Wine drinkers (W). The animals were fed synthetic diets (Lieber type) with ethanol or wine substituted isocalorically for carbohydrates in the diet of E and W groups, respectively. W received a volume of wine which provided the same gram quantity of alcohol consumed by E. The animals were sacrificed by decapitation after 6 weeks and the livers processed for quantitative triglycerides (T3), proteins, malic enzyme activity (MEA), light microscopy (LM) and electron microscopy (EM). Morphometric analysis of randomly selected LM and EM micrographs was performed to determine organellar changes in centrilobular (CV) and periportal (PV) regions of the liver. This analysis (Table 1) showed that hepatocytes from E were larger than those in C and W groups. Smooth endoplasmic reticulum decreased in E and increased in W compared to C values.

Triple Fixation For Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 90-91 ◽  
Author(s):  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Plasma Membrane ◽  
Myelin Sheath ◽  
Good Deal ◽  
Granular Structure ◽  
Oxidizing Agent ◽  
Fixation Technique ◽  
Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

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