The ultrastructure of Geotrichum candidum hyphae

1973 ◽  
Vol 19 (12) ◽  
pp. 1507-1512 ◽  
Author(s):  
S. D. Steele ◽  
T. W. Fraser
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Apical Cell ◽  
Cell Types ◽  
Geotrichum Candidum ◽  
Wall Material ◽  
Surrounding Cell ◽  
Golgi Bodies ◽  
Apical Cells ◽  
Intranuclear Microtubules

Complete septa divide the hyphae of Geotrichum candidum into many compartments or cells. Two cell types are readily recognizable, (i) the apical cell, delimited by one septum and the surrounding cell wall, and (ii) the sub- or non-apical cell, delimited by two septa and the surrounding cell wall. Vacuolation of the apical cells is slight compared with that of subapical cells. Apical cells contain many vesicles, some of which are elongated and branched, possibly forming an interconnecting tubular network; other vesicles were observed distributed about the apical zone or aggregated to form an apical body (the Spitzenkörper). Vesicles are also evident in subapical cells, but only in association with developing septa. Golgi bodies were not observed in any cells, their function in vesicle production possibly being taken by a modification of part of the endoplasmic reticulum. Both cell types contained mitochondria with contrasting electron-staining properties. Some stages of mitosis were observed. The nucleus appears to retain its envelope throughout division and exhibits intranuclear microtubules attached to spindle plaques. Septa were formed by a centripetal deposition of wall material, plasmodesmata developing during this process. Another deposition of wall material occurs after the centripetal deposition thus allowing a secondary thickening of the septum to take place.

scholarly journals The amounts and rates of export of polysaccharides found within the membrane system of maize root cells

1974 ◽  
Vol 142 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Dianna J. Bowles ◽  
D. H. Northcote
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Golgi Apparatus ◽  
Cell Surface ◽  
Rough Endoplasmic Reticulum ◽  
Membrane System ◽  
Maize Root ◽  
Wall Material ◽  
Cell Wall Material ◽  
Root Cells

1. Maize seedling roots were incubated in vivo with d-[U-14C]glucose for 2, 5, 10, 15, 30 and 45min. The total incorporation of radioactivity into polysaccharide components in isolated fractions was investigated, and the pattern of incorporation into different polysaccharide components within the rough endoplasmic reticulum, Golgi apparatus and exported material was analysed. 2. The membrane compartments reached a saturation value of radioactivity in polysaccharide components by 30min incubation. Radioactivity in exported polysaccharide continued to increase after that time. The latter was formed and maintained by a steady-state turnover of polysaccharide synthesis and transport from the membrane system. 3. If the only access of the slime polysaccharide to the cell surface is via dictyosome-derived vesicles, the amount of slime components in the Golgi apparatus would have to be displaced every 0.3min in order to maintain the observed rates of increase in slime. This is in contrast with a displacement time of about 2.5min that is necessary for polysaccharide components in the Golgi apparatus to produce the observed increase in cell-wall material. The activity of the membrane system in the production of maize root slime is 8 times as great as that of the membrane system involved in cell-wall synthesis. 4. If the amount of polysaccharide material in the Golgi apparatus is maintained only by inflow of polymeric material from the rough endoplasmic reticulum the total amount of slime components in the rough endoplasmic reticulum would have to be displaced every 7min to maintain a constant amount in the Golgi apparatus. If the endoplasmic reticulum contributed directly to the cell surface in the synthesis of cell-wall material, displacement times necessary to maintain the observed rate of polymer production would be very slow.

Fine structure of the thraustochytrid Ulkenia amoeboidea. I. Vegetative thallus and formation of the amoeboid stage

1982 ◽  
Vol 60 (7) ◽  
pp. 1092-1102 ◽  
Author(s):  
S. Raghu Kumar
Keyword(s):  
Cell Wall ◽  
Close Association ◽  
Ultrastructural Level ◽  
Wall Material ◽  
Unit Membrane ◽  
Golgi Bodies ◽  
Young Thalli ◽  
Mature Thallus ◽  
Filamentous Material ◽  
Dense Inclusion

Development of the thraustochytrid Ulkenia amoeboidea was investigated at the ultrastructural level. The mature thallus possesses a lamellate wall, a nucleus with intranuclear vesicles and lamellae, several Golgi bodies, mitochondria, bundles of microfilaments, multivesicular bodies, dilated perinuclear continuum with filamentous material, endoplasmic reticulum, sagenogenetosomes, and two centrioles. Several unit membrane bounded, variously electron-dense inclusion bodies with electron-dense globular units are present. Wall scales are produced in Golgi cisternae which inflate to form vesicles. These vesicles deposit the wall material to the outside by exocytosis. An aggregate of unit membrane bounded electron-dense cisternae (paranuclear body) is found adpressed to the nucleus. A close association between the paranuclear body and the mitochondria, the former often producing finger-like projections in mitochondrial vicinity, is present. A protocentriole-like structure is seen near the nucleus of young thalli. At later stages, the ectoplasmic net elements disappear. Closely adpressed membrane arrays appear between the cell wall and plasmalemma. These are accumulated in bundles at various places in the cell and are later found in presumed autophagic vacuoles. Before the cell contents escape as an amoeboid mass, the cell wall becomes thinner owing to the peeling off of wall scales and the cell contents round up, with the plasmalemma becoming detached from the cell wall. Various vesicles are closely associated with the plasmalemma.

Fine structure of the thraustochytrid Ulkenia amoeboidea. II. The amoeboid stage and formation of zoospores

1982 ◽  
Vol 60 (7) ◽  
pp. 1103-1114 ◽  
Author(s):  
S. Raghu Kumar
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Nuclear Division ◽  
Smooth Endoplasmic Reticulum ◽  
Dense Granule ◽  
Multivesicular Bodies ◽  
Golgi Bodies ◽  
Dense Bodies ◽  
Spindle Microtubules

In the thraustochytrid Ulkenia amoeboidea (Bahnweg & Sparrow) Gaertner the contents of the mature vegetative thallus escape from the cell wall in the form of a limax cell. The limax cell is covered by a layer of scales and possesses a nucleus, a paranuclear body, Golgi bodies, mitochondria, bands of smooth endoplasmic reticulum, vacuoles, multivesicular bodies, and cisternae with filamentous contents. The posterior end is filled with smooth endoplasmic reticulum and fusiform vesicles. The anterior end is organelle free and filled with cytoplasm with free ribosomes. Subspherical dense bodies, bounded by a single membrane, are present. The limax cell rounds up prior to mitosis and the Golgi bodies increase in number. During mitosis, the nuclear membrane breaks down totally. Chromosomes are not well defined. Spindle microtubules arise from the centriole and enter the nucleus. After nuclear division, the nuclear envelope is reformed. Cytokinesis is by cleavage into two cells, accompanied by formation of microtubules along the cleavage furrows. The zoospore possesses a nucleus, a paranuclear body, mitochondria, vesicles with presumptive mastigonemes and kinetosome rootlet microtubules and they are covered by a layer of scales. An electron-dense granule and two peripheral thickenings are present within the lumen of the kinetosome.

Ultrastructural changes during germination of Geotrichum candidum arthrospores

1973 ◽  
Vol 19 (8) ◽  
pp. 1031-1034 ◽  
Author(s):  
S. D. Steele ◽  
T. W. Fraser
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Germ Tube ◽  
Tube Wall ◽  
Geotrichum Candidum ◽  
Spore Wall ◽  
Ultrastructural Changes ◽  
Wall Material ◽  
Apparent Increase ◽  
Tube Emergence

The dormant arthrospore in Geotrichum candidum has three, possibly four, layers making up the spore wall. Nuclei, mitochondria, free ribosomes, fragments of endoplasmic reticulum, various small vacuoles, and particles of glycogen were observed within the protoplasm. During germination a new layer of wall material forms between the original spore wall and the cytoplasm. This new layer is confined to the region where germ-tube emergence occurs and is continuous with the germ-tube wall. After germ-tube emergence vesicles were seen at the apices of germlings. Another feature of germination was an apparent increase in the amount of endoplasmic reticulum, some of which appears to assume the function of the Golgi apparatus.

Aerial root cap structure of an orchid, Epidendrum

1981 ◽  
Vol 59 (9) ◽  
pp. 1702-1708 ◽  
Author(s):  
Susan J. Blackman ◽  
Edward C. Yeung
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Cell Walls ◽  
Root Cap ◽  
Wall Material ◽  
Wall Thickening ◽  
Cell Wall Material ◽  
Random Orientation ◽  
Mitotic Figures ◽  
Distal Cell

The root cap of Epidendrum ibaguense has a rounded profile with a root cap junction present between the cap and meristem. A distinct columella region is lacking. Mitotic figures are infrequent in the root cap initial cells. The root cap initials and their immediate derivatives show few dictyosomes, little endoplasmic reticulum, plastids lacking starch, and few vacuoles. As the cells age they increase in size and show increasing vacuolation. Plastids increase by division and accumulate large starch grains. Throughout the root cap, amyloplasts maintain a random orientation in the cell. Endoplasmic reticulum also becomes more abundant as the cells age. In older cells, hypertrophied dictyosomes are evident and cell wall material begins accumulating between the distal cell wall and the plasmalemma. Wall thickening progresses with age though radial walls remain largely unthickened. Vacuolation progresses and is followed by complete senescence leaving only the cell walls.

scholarly journals The Fine Structure of the Parathyroid Gland

1958 ◽  
Vol 4 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Jerry Steven Trier
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Connective Tissue ◽  
Light Microscope ◽  
Parenchymal Cell ◽  
Cell Types ◽  
Perivascular Spaces ◽  
Chief Cells ◽  
Golgi Bodies ◽  
Endocrine Tissues

The fine structure of the parathyroid of the macaque is described, and is correlated with classical parathyroid cytology as seen in the light microscope. The two parenchymal cell types, the chief cells and the oxyphil cells, have been recognized in electron micrographs. The chief cells contain within their cytoplasm mitochondria, endoplasmic reticulum, and Golgi bodies similar to those found in other endocrine tissues as well as frequent PAS-positive granules. The juxtanuclear body of the light microscopists is identified with stacks of parallel lamellar elements of the endoplasmic reticulum of the ergastoplasmic or granular type. Oxyphil cells are characterized by juxtanuclear bodies and by numerous mitochondria found throughout their cytoplasm. Puzzling lamellar whorls are described in the cytoplasm of some oxyphil cells. The endothelium of parathyroid capillaries is extremely thin in some areas and contains numerous fenestrations as well as an extensive system of vesicles. The possible significance of these structures is discussed. The connective tissue elements found in the perivascular spaces of macaque parathyroid are described.

The mechanism of surface growth in parenchyma of Avena coleoptiles

1955 ◽  
Vol 3 (2) ◽  
pp. 137 ◽  
Author(s):  
AB Wardrop
Keyword(s):  
Cell Wall ◽  
Tip Growth ◽  
Cell Types ◽  
Cellulose Microfibrils ◽  
Wall Material ◽  
Cell Wall Material ◽  
Cell Enlargement ◽  
Electron Microscopic ◽  
Stages Of Growth ◽  
Preferred Direction

A study has been made of the organization of the cell wall in the parenchyma of Avena coleoptiles at successive stages of growth, using light and electron microscopic methods. It has been observed that extension of the parenchyma involves a progressive separation of the primary pit fields accompanied by an increasing dispersion of the cellulose microfibrils about their preferred direction of orientation. On the basis of this, and ancillary evidence from other cell types, it is suggested that extension growth involves stretching of the cell with the intercalation of new microfibrils into the expanding cell wall framework from the regions of the primary pit fields and penetration of the cell wall by plasmodesmata. It is considered that the evidence is consistent equally with the view either that the cell wall is stretched as water absorption accompanying enlargement takes place, or that cell enlargement is controlled by the synthesis of cell wall material at synthetic centres (pit fields and plasmodesmata) distributed over the cell surface. The concept of bipolar tip growth for coleoptile parenchyma is rejected.

Electron microscopy of the conidial protoplasts of Neurospova crassa

1968 ◽  
Vol 46 (12) ◽  
pp. 1561-1564 ◽  
Author(s):  
M. S. Manocha
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Conidial Germination ◽  
Cell Wall Structure ◽  
Wall Material ◽  
Wall Structure ◽  
Protoplast Formation ◽  
Small Pore ◽  
Similarities And Differences

Micromorphology of conidia resembles that of young hyphae except for the details of the cell wall structure, which is thicker and prominently developed in unhydrated conidia. Although mitochondria and endoplasmic reticulum are present in ungerminated conidia, these organelles increase greatly during germination, and vacuoles increase in size and number. Naked protoplasts protrude through a small pore in the partially digested wall of the conidium. Free protoplasts synthesize new wall material when incubated in a regenerative mixture. Similarities and differences between conidial germination and protoplast formation and regeneration are noted.

Multivesicular structures and cell wall growth

1969 ◽  
Vol 47 (12) ◽  
pp. 1873-1877 ◽  
Author(s):  
L. C. Fowke ◽  
George Setterfield
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Physiological State ◽  
Plant Cells ◽  
Wall Material ◽  
Golgi Bodies ◽  
Wall Growth ◽  
Cell Wall Deposition ◽  
Applied Auxin ◽  
In Cells

Applied auxin caused cells of artichoke tuber slices to expand and deposit significant amounts of new wall material while cells in slices held on water remained essentially inert in both respects. Cells in all physiological treatments showed multivesicular structures at the plasma membrane (plasmalemmasomes, lomasomes), within the cytoplasm and within the central vacuoles. The number of plasmalemmasomes was considerably greater in cells not depositing wall than in cells treated with auxin to stimulate wall synthesis. Multivesicular structures showed no relation to Golgi bodies, which increase in number and apparent activity in response to auxin treatment. It is concluded that plasmalemmasomes are not involved in cell wall deposition. Multivesicular structures in plant cells could have several origins and it is suggested that some may represent artifactual reorganization of plasmalemma and tonoplast membranes during cytological processing. Such reorganization would presumably be sensitive to the physiological state of the tissue.

Development of a cellular body during differentiation of conidial chlamydospores in Fusarium

1974 ◽  
Vol 20 (9) ◽  
pp. 1205-1208 ◽  
Author(s):  
Edward F. Schneider ◽  
W. L. Seaman
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Late Stage ◽  
Cell Structure ◽  
The Body ◽  
Wall Material ◽  
Cell Wall Material ◽  
Single Membrane ◽  
Fusarium Poae ◽  
Similar Body

The development of cellular bodies during the conversion of conidial cells to chlamydospores in Fusarium sulphureum (F. sambucinum f.6) is described. Development of the bodies from dilated cisternae within the endoplasmic reticulum begins before there are other recognizable changes in cell structure and is completed before new cell wall material is laid down. Each body is bounded by a single membrane derived from the endoplasmic reticulum and contains electron-dense particles, vesicular structures, and usually a microbody. These components remain intact within the body until a late stage in chlamydospore development. At that time the contents become granular, the vesicles and microbodies disappear, and the body becomes vacuole-like. A similar body was found in cells of Fusarium poae at comparable stages of chlamydospore development.

Sign in / Sign up

Export Citation Format

Share Document