Further Observations on Scale Formation in Chrysochromulina Chiton

1967 ◽  
Vol 2 (3) ◽  
pp. 411-418
Author(s):  
IRENE MANTON
Keyword(s):  
Endoplasmic Reticulum ◽  
Normal Form ◽  
Outer Layer ◽  
Amorphous Material ◽  
Scale Formation ◽  
Outer Side ◽  
Scale Production

The normal form of the species has been compared with a deviant form and the processes of scale production in both more fully studied. The deviation is shown to be genetically based, possibly a mutation, of which the main structural expression is loss of capacity to develop the normal outer layer of material on each scale. The large scales also lack rims, a flange on the back giving a spurious resemblance to an inverted rim. A significant factor in determining orientation of the large scales appears to be a deposit of amorphous material on the morphologically outer side, which though much reduced in the deviant strain is still present. Orientation of scales in both strains of the species is therefore basically identical and independent of overall shape, though it is structurally determined before liberation from the parent Golgi cisternae. Changes in the latter have been traced up to and including the act of liberation of the contents to the exterior. This takes place near to the flagellar bases and there are some indications that participation by endoplasmic reticulum may be involved.

scholarly journals Ultrastructure and Differentiation In Chara Sp. III. Formation of the Antheridium

1968 ◽  
Vol 21 (2) ◽  
pp. 255 ◽  
Author(s):  
JD Pickett-Heaps
Keyword(s):  
Endoplasmic Reticulum ◽  
Basal Cell ◽  
Outer Layer ◽  
Distinctive Pattern ◽  
Wall Deposition ◽  
Nodal Cell ◽  
Large Numbers ◽  
Cytoplasmic Microtubules ◽  
Spermatogenous Cells

The formation of the antheridium from an enlarged nodal cell is described. After a basal cell has been cut off, precisely oriented mitoses divide the antheridial cell initially into octants; then follow two periclinal divisions in each octant. The outer layer of cells become the shield cells, the middle form the manubria, and the inner capitula cells divide further to produce secondary capitula and ultimately the spermatogenous threads. The shield cells become compartmentalized during enlargement by ingrowths in the wall which finally form a very distinctive pattern. Microtubules are associated with the regions of wall deposition. Plastids in the shields accumulate large numbers of globuli, and this is probably associated with the orange pigmentation they acquire. Large amounts of material seem to be secreted into the antheridia by the manubria; this material is formed within large vesicles which are apparently discharged through the plasmalemma. In the young capitula, a characteristic, highly organized grouping of many cytoplasmic microtubules forms a band which appears to wind through the cytoplasm; its significance and functions are obscure. Presumptive "spherosomes" are present in large numbers in these and spermatogenous cells. The spherosomes and lipid-like inclusions are very frequently coated with membranes of the endoplasmic reticulum.

The fine structure and development of chlamydospores of Fusarium oxysporum

1972 ◽  
Vol 18 (7) ◽  
pp. 997-1002 ◽  
Author(s):  
I. L. Stevenson ◽  
S. A. W. E. Becker
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cell Surface ◽  
Outer Layer ◽  
Outer Wall ◽  
Wall Layer ◽  
Thin Sections ◽  
Hyphal Wall

Methods have been developed for the rapid, reproducible induction of high-density populations of F. oxysporum chlamydospores. On transferring washed pregerminated conidia to a simple two-salts medium, chlamydospore morphogenesis was evident by 12 h and masses of mature spores could be harvested at the end of 4 days. Electron-microscope studies of thin sections of mature chlamydospores reveal a thick triple-layered cell wall. The cytoplasm contains, in addition to large lipid deposits, a nucleus, mitochondria, and endoplasmic reticulum all typical of fungal cells. Chlamydospores of F. oxysporum exhibit two distinct types of cell surface in thin section. The outer wall layer of two of the isolates studied was smooth-surfaced while the outer layer of the two other isolates was distinctly fibrillose. Some evidence is presented suggesting that the fibrillose material arises through the partial breakdown of the original hyphal wall.

Tissue reaction of Tagelus plebeius (Bivalvia: Psammobiidae) against larval digeneans in mixohaline habitats connected to the south-western Atlantic

2008 ◽  
Vol 89 (3) ◽  
pp. 569-577 ◽  
Author(s):  
Cristián Ituarte ◽  
Florencia Cremonte ◽  
Agostina Scarano
Keyword(s):  
Outer Layer ◽  
Amorphous Material ◽  
Variable Number ◽  
Tissue Reaction ◽  
Dorsal Part ◽  
Intensity Of Infection ◽  
Visceral Mass ◽  
Western Atlantic ◽  
The Family ◽  
Inner Surface

This paper describes the organism–organism relationship between a bivalve host and larval digeneans. The studied population of the stout razor clam Tagelus plebeius from the mixohaline Mar Chiquita lagoon (37° 32′S 57° 19′W) showed 100% of prevalence of infection by a larval digenean (metacercaria) of the family Gymnophallidae. The larvae occupied the extrapallial space just below the hinge of the bivalve. The tissue reaction against larval digeneans by T. plebeius consisted of hyperplasia and metaplasia of the outer layer of the mantle epithelium adjacent to parasites, forming an invagination to generate a sac that surrounded gymnophallid larvae. According to the intensity of infection, each sac progressively enlarged to harbour a variable number of larvae. In highly infected clams, a great number of sacs are formed. Eventually, the older sacs containing larvae may become closed, losing their communication with the extrapallial space and sinking into the dorsal part of the visceral mass. Larvae within sacs grow and remain alive until they reach an appropriate definitive bird vertebrate host. Older lesions commonly showed remains of dead larvae which had undergone resorption. As a result, an orange to brownish amorphous material accumulated in the space once occupied by the larvae leaving conspicuous orange marks on the inner surface of the valves. In some cases, calcifications in the form of pearls or blisters were observed.

scholarly journals Electron Microscopy of the Ovary of Fasciola Hepatica

1964 ◽  
Vol s3-105 (70) ◽  
pp. 213-218
Author(s):  
R. A. R. GRESSON
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Fasciola Hepatica ◽  
Amorphous Material ◽  
Primary Oocyte ◽  
Intercellular Region ◽  
Narrow Bridge ◽  
Peripheral Cytoplasm

The external wall of the ovary of Fasciola hepatica is a membrane-like structure in contact with a non-cellular material in the ovary. An intercellular region containing an amorphous material of moderate electron density is present in the ovary. The primary oocytes are provided with peripheral processes that extend into the intercellular region. The oocytes do not proceed beyond the prophase of the first meiotic division until after they leave the ovary. The nucleolus of the primary oocyte contains vacuole-like areas and emits granular material to the nucleoplasm; some of this material may move to the cytoplasm. Pores are present in the nuclear envelope. In older oocytes narrow bridge-like structures connect the nucleolus and the nuclear envelope. The nuclear envelope of the primary oocyte undergoes replication. It is continuous with the endoplasmic reticulum and the plasma membrane. The location of the mitochondria is correlated with the phases of growth of oogonia and oocytes. The mitochondria possess irregularly arranged cristae. Small, round or oval nutritive bodies are present in the peripheral cytoplasm of older oocytes. It is suggested that areas of relatively high density containing vacuole-like structures represent the Golgi complex.

Electron Microscopic Characterization of Insect Hemocytes

1968 ◽  
Vol 26 ◽  
pp. 68-69 ◽  
Author(s):  
Gertraude Wittig
Keyword(s):  
Endoplasmic Reticulum ◽  
Amorphous Material ◽  
Cell Type ◽  
Electron Microscopic ◽  
Ultrathin Sections ◽  
The Subject ◽  
Insect Hemocytes ◽  
Spherical Cells ◽  
Army Worm

The fine structure of insect hemocytes has been the subject of very few investigations. In particular, the hemocytes of Lepidoptera have received almost no attention. The study presented here was carried out on the armyworm, Pseudaletia unipuncta. Hemocytes of the larva were fixed 2 to 4 days after molt to the sixth instar and studied in ultrathin sections.Microplasmatocytes (Fig. 1) were the most important phagocytes of army-worm hemolymph. They were relatively small, spherical cells with a small, round or lobed nucleus. Distensions of the perinuclear cisterna (p) were frequent and sometimes continuous with the rough endoplasmic reticulum (e). The latter formed greatly distended cisternae which almost filled the whole cytoplasm. The cisternae contained an amorphous material which appeared to be condensed in certain sacs (at e). Mitochondria (m) were rare, and they had tubular cristae. Up to four Golgi complexes (g) were identified in a microplasmatocyte section. Structured granules (sg) were specific for this cell type. Microfibrils (f) traversed the whole cytoplasm but were most frequent around the nucleus (N) and under the cell membrane.

The fine structure of "resting bodies" of Bdellovibrio sp. strain W developed in Rhodospirillum rubrum

1972 ◽  
Vol 18 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Judith F. M. Hoeniger ◽  
Rita Ladwig ◽  
Hans Moor
Keyword(s):  
Outer Layer ◽  
Liquid Culture ◽  
Rhodospirillum Rubrum ◽  
Amorphous Material ◽  
Thin Sections ◽  
Host System ◽  
E Coli ◽  
Storage Granules ◽  
And Storage ◽  
Escherichia Coli B

Resting bodies of Bdellovibrio sp. strain W were produced following the infection of Rhodospirillum rubrum in liquid culture. Thin sections showed that young resting bodies possessed a narrow layer of amorphous material at their periphery, and storage granules in the region of the nucleoplasm. In mature resting bodies, the amorphous material (now called the outer layer) had thickened considerably to 30–40 nm, and the cell wall had differentiated into a folded, tripartite inner layer. Freeze-etched preparations of mature resting bodies showed a roughly particulate plasma membrane, a more finely particulate inner layer, and an outer layer having little structure.Bdellovibrio W did not produce resting bodies in a second host, Escherichia coli B. Also B. bacteriovorus strain 109 failed to form resting bodies in E. coli B, its usual host. It also failed to grow in cultures of R. rubrum. These restricted experiments suggest that the development of resting bodies may be specific for the Bdellovibrio W – R. rubrum parasite–host system.

scholarly journals The Ultrastructure of Schmidt-Lanterman Clefts and Related Shearing Defects of the Myelin Sheath

1958 ◽  
Vol 4 (1) ◽  
pp. 39-46 ◽  
Author(s):  
J. David Robertson
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Schwann Cell ◽  
Outer Layer ◽  
Dynamic Process ◽  
Myelin Sheath ◽  
The Other ◽  
Cross Sectional ◽  
Thin Sections ◽  
Sciatic Nerves

Schmidt-Lanterman clefts in frog sciatic nerves have been studied in thin sections by electron microscopy utilizing permanganate fixation and araldite embedding. It is shown that they are shearing defects in myelin in which the lamellae are separated widely at the major dense lines. Each lamella consisting of two apposed Schwann cell unit membranes ∼ 75 A across traverses the cleft intact. The unit membranes composing each lamella sometimes are slightly (∼ 50 to 100 A) separated in the clefts. The layers between the lamellae contain membranous structures which may be components of the endoplasmic reticulum. These layers are continuous with the outer layer of Schwann cytoplasm and the thin and inconstant cytoplasmic layer next to the axon (Mauthner's sheath). Each of these layers in perfect clefts constitutes a long helical pathway through the myelin from the axon. One of these is connected with Schwann cytoplasm and the other directly with the outside. A type of cross-sectional shearing defect, not hitherto recognized, is described and shown to be a kind of Schmidt-Lanterman cleft. Incomplete clefts are seen and interpreted as representing stages in a dynamic process whereby the myelin lamellae may be constantly separating and coming together again in life.

scholarly journals AUTOPHAGIC VACUOLES PRODUCED IN VITRO

1968 ◽  
Vol 38 (2) ◽  
pp. 392-402 ◽  
Author(s):  
Martha E. Fedorko ◽  
James G. Hirsch ◽  
Zanvil A. Cohn
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Amorphous Material ◽  
Continuous Phase ◽  
Electron Microscopic ◽  
Autophagic Vacuoles ◽  
Golgi Region ◽  
Microscopic Studies ◽  
Initial Action

Continuous phase-contrast observations have been made on macrophages following exposure to chloroquine. The initial abnormality is the appearance in the Golgi region of small vacuoles with an intermediate density between that of pinosomes and granules. Over the course of 1–2 hr these vacuoles grow larger and accumulate amorphous material or lipid. Pinosomes or granules frequently fuse with the toxic vacuoles. Chloroquine derivatives can be seen by fluorescence microscopy; the drug is rapidly taken up by macrophages and localized in small foci in the Golgi region. Chloroquine continues to produce vacuoles when pinocytosis is suppressed. Electron microscopic studies of chloroquine effects on macrophages preincubated with colloidal gold to label predominately pinosomes or granules suggest that toxic vacuoles can arise from unlabeled organelles. Later vacuoles regularly acquire gold label, apparently by fusion, from both granules and pinosomes. L cells also develop autophagic vacuoles after exposure to chloroquine. Smooth endoplasmic reticulum apparently is involved early in the autophagic process in these cells. Information now available suggests an initial action of chloroquine on Golgi or smooth endoplasmic reticulum vesicles, and on granules, with alterations in their membranes leading to fusion with one another and with pinosomes.

scholarly journals INTRANUCLEAR AND CYTOPLASMIC ANNULATE LAMELLAE IN TUNICATE OOCYTES

1965 ◽  
Vol 24 (3) ◽  
pp. 471-487 ◽  
Author(s):  
R. G. Kessel
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Outer Layer ◽  
Growth And Development ◽  
Granular Endoplasmic Reticulum ◽  
Fusion Process ◽  
Morphological Evidence ◽  
Annulate Lamellae ◽  
Stages Of Growth

Electron microscope studies were made on various tunicate oocytes at different stages of growth and development. Both the inner and outer lamellae of the perforated nuclear envelope demonstrate considerable blebbing activity. The blebs of the inner lamella detach into the nucleoplasm where they undergo a special type of fusion process resulting in the formation of numerous, usually single, differentiated annulate lamellae of various lengths. The blebbing of the outer layer of the nuclear envelope contributes to the vesicular and granular endoplasmic reticulum characteristically present in the ooplasm and perhaps to the differentiation of cytoplasmic annulate lamellae as well. Cytoplasmic stacks of annulate lamellae frequently have ribosomes associated with them. In addition, granular accumulations are sometimes observed around or between the annuli. The morphological evidence suggests that, at least in many cases, the annuli in the annulate lamellae are patent.

scholarly journals THE FINE STRUCTURE OF BONE CELLS

1961 ◽  
Vol 11 (3) ◽  
pp. 627-649 ◽  
Author(s):  
H. Robert Dudley ◽  
David Spiro
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Bone Cells ◽  
Amorphous Material ◽  
Granular Endoplasmic Reticulum ◽  
Lamellar Bone ◽  
Cell Surfaces ◽  
Progressive Reduction ◽  
Electron Microscopic ◽  
Cytoplasmic Processes

An electron microscopic study of Araldite-embedded, undecalcified human woven and chick lamellar bone is presented. The fine structure of the cells of bone in their normal milieu is described. Active osteoblasts possess abundant granular endoplasmic reticulum, numerous small vesicles, and a few secretion droplets. Their long cytoplasmic processes penetrate the osteoid. The transition of osteoblasts into osteoid osteocytes and then into osteocytes is traced and found to involve a progressive reduction of cytoplasmic organelles. Adjoining the osteocytes and their processes is a layer of amorphous material which is interposed between the cell surfaces and the bone walls of their respective cavities. Osteoclasts contain numerous non-membrane-associated ribosomes, abundant mitochondria, and little granular endoplasmic reticulum, thus differing markedly from other bone cells. The brush border is a complex of cytoplasmic processes adjacent to a resorption zone in bone. No unmineralized collagen is seen at resorption sites and it appears that collagen is removed before or at the time of mineral solution. All bone surfaces are covered by cells, some of which lack distinctive qualities and are designated endosteal lining cells. The structure of osteoid, bone, and early mineralization sites is illustrated and discussed.

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