The Giant Mitochondria of Ctenophore Comb-Plates

1964 ◽  
Vol s3-105 (71) ◽  
pp. 301-310
Author(s):  
G. A. HORRIDGE
Keyword(s):  
Nuclear Membrane ◽  
Amorphous Material ◽  
Ciliated Cells ◽  
Giant Mitochondria ◽  
Intimate Relation ◽  
Food Particles ◽  
Mitochondrial Origin ◽  
As If

The elongated cells which bear the continually active giant cilia of the combs contain numerous large mitochondria, up to 8 µ by 6 µ in size, which are filled with irregular tubular cristae. The ciliated cells are up to 100 µ long, but only 10 µ wide, and from their centrally situated nucleus can be traced a succession of stages, tentatively interpreted as the formation, growth, erosion, and final dissolution of mitochondria. Small ones occur near the nucleus in the region of the nuclear membrane, which may there be irregular, puffy, and electron dense. Some small mitochondria are surrounded by amorphous material which stains heavily with lead; others lie against the nuclear membrane, as if in intimate relation with it. Cristae of mitochondria which are interpreted as juvenile are filled with an amorphous material; some of the cristae open to the outside of the mitochondrion. Towards the ciliated end of the cells the appearance of the mitochondria suggests that they are breaking down; this is the region where food particles are eroded and where the cilia consume energy. Here the mitochondria are shrunken and around them are numerous vesicles; their cristae are fewer and they open into the cytoplasm. Similar vesicles, which are apparently of mitochondrial origin, are extruded between the cilia from the cells. The proposed cycle of generation and disintegration of mitochondria, based upon morphology, is so far an unproved hypothesis.

Memoirs: On the Structure of the Ovary and the Ovarian Ovum of Loris lydekkerianus, Cabr

1927 ◽  
Vol s2-71 (281) ◽  
pp. 57-74
Author(s):  
C.R. NARAYAN RAO
Keyword(s):  
Nuclear Membrane ◽  
Interstitial Cells ◽  
The Other ◽  
Follicle Cells ◽  
General Distribution ◽  
Catalytic Activities ◽  
Golgi Bodies ◽  
Intimate Relation ◽  
Nuclear Changes ◽  
Fat Bodies

There is a definite polarity in the ovarian ova as regards the distribution of the fat-bodies in the younger as well as the fully grown examples. It has not been possible to distinguish two types of ova based on the size or distribution of these deutoplasmic inclusions. The deutoplasmic pole is occupied by fat-bodies of uniformly small size, while the periphery and the plastic or nuclear pole are distinguished by the occurrence of small and large varieties of fat-spherules. Nuclear emission takes place very early in the growth of the ovum and initiates the formation of fat-bodies, and in doing so the nucleolus itself increases in size, while in the final stages of its catalytic activities it diminishes before final expulsion into the follicle cells where it is absorbed. The formation of yolk-disks is attributable to the agency of micrometachondria whose general distribution accords with the appearance of yolk and with which they are in intimate relation. Having given rise to the yolk-disks, they disappear from the fully grown ova. The Golgi bodies also initiate the formation of yolk which appears in the archoplasm, and in this process the Golgi rods are noticed to undergo appreciable diminution in size. Later in the development of the ovum the Golgi rods form a close cap on the nuclear membrane, and those which have not participated in the formation of yolk lie scattered in the general cytoplasm. Deep imaginations and their secondary ramifications occur in the ovary throughout the life of the lemur, and fresh ova arise from the germinal layers of these invaginations as well as the interstitial cells. The nuclear changes involved in the production of fresh ova are in accord with the observations already published by the other authors who have studied these changes in the rabbit, and the only point worth recording is that the diplotenic stage is less clearly marked and the dictyate stage is speeded up in the lemur.

scholarly journals Cell Division in Oedogonium I. Mitosis, Cytokinesis, and Cell Elongation I. Mitosis, Cytokinesis, and Cell Elongation

1969 ◽  
Vol 22 (4) ◽  
pp. 857 ◽  
Author(s):  
JD Prokett-Heaps ◽  
LC Fowke
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Nuclear Membrane ◽  
Cell Elongation ◽  
Chromatin Condensation ◽  
Amorphous Material ◽  
Turgor Pressure ◽  
Characteristic Structure ◽  
Lower Lip ◽  
Sequence Of Events

Development of new processing techniques has enabled a light-and electron-microscopic study of cell division in Oedoyonium to be made; many unusual or unique features are described. A series oflight micrographs confirms the sequence of events described by earlier workers. Splitting of the cell wall at the ring has been observed in vivo; the rupture is often quite violent, and subsequent elongation is rapid for a short while. At the ultrastructural level, the premitotic movement of the spherical nucleus towards the wall ring coincides with the appearance of some nearby micro-tubules. The preprophase nucleus enlarges and becomes flattened and spindle-shaped as a sheath of microtubules envelopes it. The nuclear membrane at each pole is very drawn out, appearing as two closely apposed membranes undulating into the cytoplasm; between the membranes is a dense amorphous material, and around them are longitudinally oriented microtubules. During prophase, chromatin condensation accompanies nucleolar dispersion. Microtubules start appearing within the nuclear membrane which remains essentially intact throughout subsequent division. At prometaphase, intranuclear microtubules increase and some are attached to diffuse scattered kinetochores. By metaphase, many bundles of microtubules are attached to paired kinetochores, which have a complex, layered structure. Separated kinetochores are visible at anaphase. At telophase, the spindle becomes very elongated, and many interzonal microtubules appear. A granular and heavily staining "midbody" is found between the nuclei, and this later disperses. The daughter nuclei then come very close together, and between them is found a complex of vesicles and microtubules. A septum is then formed across the cell, evidently by these microtubules (accompanied by the vesicles) pushing out the tonoplast across the vacuole till partitioning is accomplished. The nuclei then separate prior to wall splitting. The ring formed at one end of the cell has a highly characteristic structure with two lips of toughened material at its outer edge attached to the outer wall; splitting of the older wall occurs between these lips. A proliferation oflarge, electron-transparent golgi vesicles was apparent at this stage; these were apparently being discharged into the vacuole, and so may have been associated with a possible build-up of turgor pressure within the cells. The soft material of the ring is drawn out between the lips during cell elongation. The septum (still composed of vesicles and microtubules) moves up the cell like a diaphragm, eventually reaching the bottom lip of the extended ring structure. Coalescence of vesicles then occurs in the septum to form the new transverse wall attached to the lower lip from the ring. The extensible material of the ring becomes the outer layer of the cell (mucilage?); the cell wall proper is evidently formed as a thinner layer on the inside edge of this diffuse material. It is therefore suggested that the formation of wall rings, characteristic of cell division in Oedoyonium, represents an adaptation of more usual processes of algal mucilage secretion.

Giant mitochondria distinct from enlarged mitochondria in secretory and ciliated cells of gerbil trachea and bronchioles

1990 ◽  
Vol 188 (3) ◽  
pp. 269-281 ◽  
Author(s):  
S. S. Spicer ◽  
R. T. Parmley ◽  
L. Boyd ◽  
B. A. Schulte
Keyword(s):  
Ciliated Cells ◽  
Giant Mitochondria

Ultrastructure of Giant Mitochondria and Their Inclusions in Schwann Cells of Bovine Splenic Nerve

1974 ◽  
Vol 32 ◽  
pp. 194-195
Author(s):  
Å. Thureson-Klein
Keyword(s):  
Schwann Cells ◽  
Cell Organelles ◽  
Giant Mitochondria ◽  
Matrix Density ◽  
Physiological Conditions ◽  
Unmyelinated Axons ◽  
Internal Structures ◽  
Structural Abnormalities ◽  
Cytotoxic Compounds ◽  
Cell Components

Giant mitochondria of various shapes and with different internal structures and matrix density have been observed in a great number of tissues including nerves. In most instances, the presence of giant mitochondria has been associated with a known disease or with abnormal physiological conditions such as anoxia or exposure to cytotoxic compounds. In these cases degenerative changes occurred in other cell organelles and, therefore the giant mitochondria also were believed to be induced structural abnormalities.Schwann cells ensheating unmyelinated axons of bovine splenic nerve regularly contain giant mitochondria in addition to the conventional smaller type (Fig. 1). These nerves come from healthy inspected animals presumed not to have been exposed to noxious agents. As there are no drastic changes in the small mitochondria and because other cell components also appear reasonably well preserved, it is believed that the giant mitochondria are normally present jin vivo and have not formed as a post-mortem artifact.

The Formation, Structure, Distribution and Frequency of Nuclear Pores

1971 ◽  
Vol 29 ◽  
pp. 518-519
Author(s):  
G. G. Maul
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Dynamic Structure ◽  
Nuclear Pore ◽  
Nuclear Pores ◽  
Filter Function ◽  
Etching Technique ◽  
Selective Filter ◽  
Membranous Part

The chromatin of eukaryotic cells is separated from the cytoplasm by a double membrane. One obvious structural specialization of the nuclear membrane is the presence of pores which have been implicated to facilitate the selective nucleocytoplasmic exchange of a variety of large molecules. Thus, the function of nuclear pores has mainly been regarded to be a passive one. Non-membranous diaphragms, radiating fibers, central rings, and other pore-associated structures were thought to play a role in the selective filter function of the nuclear pore complex. Evidence will be presented that suggests that the nuclear pore is a dynamic structure which is non-randomly distributed and can be formed during interphase, and that a close relationship exists between chromatin and the membranous part of the nuclear pore complex.Octagonality of the nuclear pore complex has been confirmed by a variety of techniques. Using the freeze-etching technique, it was possible to show that the membranous part of the pore complex has an eight-sided outline in human melanoma cells in vitro. Fibers which traverse the pore proper at its corners are continuous and indistinguishable from chromatin at the nucleoplasmic side, as seen in conventionally fixed and sectioned material. Chromatin can be seen in octagonal outline if serial sections are analyzed which are parallel but do not include nuclear membranes (Fig. 1). It is concluded that the shape of the pore rim is due to fibrous material traversing the pore, and may not have any functional significance. In many pores one can recognize a central ring with eight fibers radiating to the corners of the pore rim. Such a structural arrangement is also found to connect eight ribosomes at the nuclear membrane.

Glass Knife Geometry as Seen by the SEM

1971 ◽  
Vol 29 ◽  
pp. 454-455
Author(s):  
J. Temple Black
Keyword(s):  
Low Cost ◽  
Amorphous Material ◽  
Stress Concentrations ◽  
Basic Tool ◽  
Tool Materials ◽  
Optical Inspection ◽  
Surface Flaws ◽  
Slip Planes ◽  
Glass Knife ◽  
Diamond Knife

In ultramicrotomy, the two basic tool materials are glass and diamond. Glass because of its low cost and ease of manufacture of the knife itself is still widely used despite the superiority of diamond knives in many applications. Both kinds of knives produce plastic deformation in the microtomed section due to the nature of the cutting process and microscopic chips in the edge of the knife. Because glass has no well defined slip planes in its structure (it's an amorphous material), it is very strong and essentially never fails in compression. However, surface flaws produce stress concentrations which reduce the strength of glass to 10,000 to 20,000 psi from its theoretical or flaw free values of 1 to 2 million psi. While the microchips in the edge of the glass or diamond knife are generally too small to be observed in the SEM, the second common type of defect can be identified. This is the striations (also termed the check marks or feathers) which are always present over the entire edge of a glass knife regardless of whether or not they are visable under optical inspection. These steps in the cutting edge can be observed in the SEM by proper preparation of carefully broken knives and orientation of the knife, with respect to the scanning beam.

New Ultrastructural Observations on Injury and Regeneration of Cilia in Mammalian Conducting Airway Epithelium

1981 ◽  
Vol 39 ◽  
pp. 624-625
Author(s):  
J.L. Carson ◽  
A.M. Collier
Keyword(s):  
Respiratory Tract ◽  
Airway Epithelium ◽  
Defense Mechanisms ◽  
Normal Growth ◽  
Fetal Lung ◽  
Secretory Cells ◽  
Airway Epithelial ◽  
Ciliated Cells ◽  
Conducting Airway ◽  
Conducting Airways

The ciliated cells lining the conducting airways of mammals are integral to the defense mechanisms of the respiratory tract, functioning in coordination with secretory cells in the removal of inhaled and cellular debris. The effects of various infectious and toxic agents on the structure and function of airway epithelial cell cilia have been studied in our laboratory, both of which have been shown to affect ciliary ultrastructure.These observations have led to questions about ciliary regeneration as well as the possible induction of ciliogenesis in response to cellular injury. Classical models of ciliogenesis in the conducting airway epithelium of the mammalian respiratory tract have been based primarily on observations of the developing fetal lung. These observations provide a plausible explanation for the embryological generation of ciliary beds lining the conducting airways but do little to account for subsequent differentiation of ciliated cells and ciliogenesis during normal growth and development.

Ultrastructure of bronchopulmonary lavage cells from bovines administered 3-methylindole: II. 24 hours post-treatment

1984 ◽  
Vol 42 ◽  
pp. 202-203
Author(s):  
Amreek Singh ◽  
Judith M. McLaren ◽  
Onkar S. Atwal ◽  
Peter Eyre
Keyword(s):  
Plasma Cells ◽  
Ciliated Cell ◽  
Lavage Fluid ◽  
Treated Group ◽  
Post Treatment ◽  
Lung Edema ◽  
Ciliated Cells ◽  
Thin Sections ◽  
Variable Diameter ◽  
Cell Pellet

Introduction3-methylindole (MI), a rumen metabolite of the amino acid L-tryptophan, has been shown to produce bovine pulmonary edema and emphysema. The airways contain free and exfoliated cells. A morphologic analysis of these cells may complement the understanding of the mechanism of lung edema. Ultrastructure of the bronchopulmonary lavage (BL) cells 24 h following MI oral administration to calves is described in this experiment. The 12 hours post-treatment results were described earlier.Materials and MethodsTwo Holstein-Friesian calves were each administered an oral dose of 0.2 g MI/Kg body weight and another two calves served as controls. The animals were euthanized with sodium pentabarbitol 24 h after receiving the compound. The lungs and trachea were removed and 0.1 M sodium phosphate buffered saline was infused into the lungs through the trachea. Glutaraldehyde fixative was added to the recovered BL fluid so as to form a 1% solution. The fluid was centrifuged and the resulting cell pellet was suspended in the buffer. The procedures were repeated on the suspension; the pellet was post-fixed in osmium tetroxide and was processed by conventional methods of section preparations for TEM examination. Lung samples from caudal lobes were fixed in 1.5% glutaraldehyde to obtain tissue sections for TEM.Results and DiscussionPulmonary alveolar macrophages (AM), neutrophils, ciliated epithelial cells, globule leukocytes and plasma cells were recovered from the BL fluid of the control and Mi-administered calves. Ciliated cells and globule leukocytes could not be harvested from the controls. The AM obtained from the treated calves (Fig. 1) in comparison with similar cells from the controls were larger, and contained large membrane-limited inclusions (phagolysosomes). There was a remarkable similarity between the lavaged AM and the AM studied in thin sections of lung (cf. Fig. 1 and Fig. 2). The neutrophil was the second most abundant cell type retrieved from the lavage fluid from the calves of control or treated group. Except for scanty pseudopodia in the neutrophils obtained from the Mi-receiving calves, the cells appeared unaltered (Fig. 3). Ciliated cells were abundant in the BL fluid of Mi-ingesting calves. A heterogeneous collection of vesicles filled the ciliated cell cytoplasm (Fig. 3). Globule leukocytes were commonly observed among BL cells of treated calves. The globule leukocytes were ca. 15 μm in diameter and contained round or elliptical nuclei with conspicuous nucleoli. The cytoplasmic granules, which are a prominent feature of globule leukocytes, were electron-opaque and had a variable diameter (0.5-3.0 μm). A one-line account of globule leukocytes in the bronchi of steers administered MI has appeared. Plasma cells were rare. Ultrastructure of BL cells is compatible with their response to chemical insult by MI.

Scanning and Transmission Electron Microscopy of the Endometrium in Women with Ovarian Dysgenesis (Turner'S Syndrome)

1976 ◽  
Vol 34 ◽  
pp. 148-149
Author(s):  
A. González-Angulo ◽  
S. Armendares-Sagrera ◽  
I. Ruíz de Chávez ◽  
H. Marquez-Monter ◽  
R. Aznar
Keyword(s):  
Surface Epithelium ◽  
Secretory Cells ◽  
Turner's Syndrome ◽  
Ciliated Cells ◽  
Turner’S Syndrome ◽  
Exogenous Hormone ◽  
Ovarian Dysgenesis ◽  
Transmission Electron ◽  
Normal Women ◽  
Microscopy Examination

It is a well documented fact that endometrial hyperplasia and adenocarcinoma may develop in women with Turner's syndrome who had received unopposed estrogen treatment (1), as well as in normal women under contraceptive medication with the sequential regime (2). The purpose of the present study was to characterize the possible changes in surface and glandular epithelium in these women who were treated with a sequential regime for a period of between three and eight years. The aim was to find organelle modifications which may lead to the understanding of the biology of an endometrium under exogenous hormone stimulation. Light microscopy examination of endometrial biopsies of nine patients disclosed a proliferative pattern; in two of these, there was focal hyperplasia. With the scanning electron microscope the surface epithelium in all biopsies showed secretory cells with microvilli alternating with non secretory ciliated cells. Regardless of the day of the cycle all biopsies disclosed a large number of secretory cells rich in microvilli (fig.l) with long and slender projections some of which were branching (fig. 2).

An Ultra-Structural Study of Human Melanoma in Vivo and Vitro

1976 ◽  
Vol 34 ◽  
pp. 258-259
Author(s):  
James R. Gaylor ◽  
Fredda Schafer ◽  
Robert E. Nordquist
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Protein Aggregation ◽  
Structural Study ◽  
Human Melanoma ◽  
Protein Matrix ◽  
Early Form ◽  
Endoplasmic Reticulum Protein ◽  
Mitochondrial Origin

Several theories on the origin of the melanosome exist. These include the Golgi origin theory, in which a tyrosinase-rich protein is "packaged" by the Golgi apparatus, thus forming the early form of the melanosome. A second theory postulates a mitochondrial origin of melanosomes. Its author contends that the melanosome is a modified mitochondria which acquires melanin during its development. A third theory states that a pre-melanosome is formed in the smooth or rough endoplasmic reticulum. Protein aggregation is suggested by one author as a possible source of the melanosome. This fourth theory postulates that the melanosome originates when the protein products of several genetic loci aggregate in the cytoplasm of the melanocyte. It is this protein matrix on which the melanin is deposited. It was with these theories in mind that this project was undertaken.

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