Fine structure of the septum in Wallemia sebi

1974 ◽  
Vol 52 (12) ◽  
pp. 2587-2590 ◽  
Author(s):  
Fred C. Terracina
Keyword(s):  
Fine Structure ◽  
Dense Region ◽  
Yeast Genus ◽  
Ascomycetous Yeast ◽  
Wallemia Sebi ◽  
Central Pore ◽  
Oriented Parallel

The septa of the deuteromycete Wallemia sebi (Fr.) v. Arx have expanded pore margins surrounding a central pore and lack parenthesomes. At each end of the pore there is an electron-dense region with a distinct five-banded pattern (three electron-dense bands separated by two less-electron-dense bands) oriented parallel to the septum. These septa are compared with similar septa in phycomycetes, the dolipore septa reported in the ascomycetous yeast genus Ambrosiozyma and the dolipore–parenthesome septa of the basidiomycetes. It is proposed that the term dolipore be applied to any septum having expanded pore margins.

scholarly journals THE ULTRASTRUCTURE OF CARDIAC DESMOSOMES IN THE TOAD AND THEIR RELATIONSHIP TO THE INTERCALATED DISC

1960 ◽  
Vol 8 (2) ◽  
pp. 305-318 ◽  
Author(s):  
Philip M. Grimley ◽  
George A. Edwards
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Cardiac Cells ◽  
Dense Region ◽  
Intercalated Disc ◽  
Outer Coat ◽  
Intercalated Discs ◽  
Simple Step ◽  
Contractile Forces ◽  
Band Material

The fine structure of desmosomes and intercalated discs in the toad heart is discussed. A definite relationship between the dense components of these structures and the dense region of the Z band is demonstrated. The dense region of the Z band characteristically widens at its approach to the plasma membrane, and often terminates beneath it in a distinct discoidal plaque. Cardiac desmosomes appear to be structures which result from the intimate apposition of plaques of Z band material. These desmosomes retain the Z band function as sites of attachment for myofilaments. The suggestion is made that rotation of a desmosome through 90° and splitting of filaments from the adjacent sarcomere could result in the formation of a simple step-like intercalated disc. Intermediate stages in this process are illustrated. Complex discs present in the toad probably represent the alignment of groups of simple discs produced by contractile forces. Possible physiologic functions of the disc and desmosome are discussed. Other morphologic features of toad cardiac cells include a distinct amorphous outer coat to the sarcolemma, a prominent N band, and a granular sarcoplasm with poorly developed reticulum.

scholarly journals FINE STRUCTURE AND REPLICATION OF THE KINETOPLAST OF TRYPANOSOMA LEWISI

1968 ◽  
Vol 39 (2) ◽  
pp. 318-331 ◽  
Author(s):  
Paul R. Burton ◽  
Donald G. Dusanic
Keyword(s):  
Fine Structure ◽  
Physiological State ◽  
Trypanosoma Lewisi ◽  
Left And Right ◽  
Morphological Differences ◽  
Oriented Parallel ◽  
Silver Grains

The kinetoplastic DNA of Trypanosoma lewisi is described as a filamentous body lying within a mitochondrion, with the filaments oriented parallel to the long axis of the cell. The manner of fixation, the replicative state, and perhaps the physiological state of the cell, may result in slight morphological differences among such bodies. The kinetoplastic DNA replicates to form "left" and "right" rather than "upper" and "lower" members, and both the kinetoplast and nucleus incorporate radiothymidine as shown by radioautography. Radioautographic analyses suggest a random incorporation of radiothymidine by kinetoplasts. Silver grains were occasionally observed over centriolar elements. Finally, the observations are discussed with respect to the sequential replication of the aforementioned organelles by T. lewisi.

scholarly journals Shape in relation to fine structure in the bristles of Drosophila melanogaster

1945 ◽  
Vol 132 (869) ◽  
pp. 396-423 ◽  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Drosophila Melanogaster ◽  
Fine Structure ◽  
Anisotropic Medium ◽  
Mode Of Action ◽  
Close Correspondence ◽  
Yield Value ◽  
Optical And Mechanical Properties ◽  
Oriented Parallel

The bristles of Drosophila melanogaster have provided material for a study of the relation between the shape of a specialized type of cell and the orientation of the chitin molecules of the cell wall, as revealed by optical and mechanical properties. Close correspondence between shape and orientation has been found, both in normal and mutant bristles. Certain of the mechanical properties of the wall of the adult bristle can be studied directly, and something of those of the immature wall can be inferred from the behaviour of the bristle during develop­ment. There is reason to believe that the newly formed wall is plastic and that it possesses a definite yield value. The bristle may be regarded as a hollow object blown in a plastic, anisotropic medium by the pressure of cytoplasm formation in the trichogen. It seems reasonable to suppose that the shape of the normal bristle is intimately related to the growth in length of the chitin chains of the cell wall oriented parallel to the long axis of the cell. Indeed the long axis appears to be such because the oriented chains grow in its direction. Our study of mutant as well as normal bristles has enabled us to make a tentative analysis of the factors concerned in their growth, and to suggest what may be the mode of action of those genes which modify the shape of the bristle. We are led to an interpretation of the shape of the bristle in terms of the properties of the substances secreted by the trichogen (wall-substance and cytoplasm) and of the time relations of their synthesis.

scholarly journals ULTRASTRUCTURE OF THE SPOON TYPE SYNAPTIC ENDINGS IN THE NUCLEUS VESTIBULARIS TANGENTIALIS OF THE CHICK

1967 ◽  
Vol 34 (2) ◽  
pp. 421-430 ◽  
Author(s):  
Raúl Hinojosa ◽  
J. David Robertson
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Synaptic Vesicles ◽  
Synaptic Cleft ◽  
Synaptic Membrane ◽  
Electrical Transmission ◽  
Membrane Complex ◽  
Pattern Characteristic ◽  
Oriented Parallel ◽  
Nucleus Vestibularis

The fine structure of the "spoon" type synaptic endings of the chick tangential nucleus was studied with the electron microscope. These endings often measure ∼18 µ in length by ∼3–4 µ in width. The axoplasm of the endings contains very few synaptic vesicles, a large number of neurofilaments oriented parallel to the long axis of the nerve fiber, and microtubules and numerous mitochondria. The synaptic membrane complex shows areas of localized occlusion of the synaptic cleft with the formation of an external compound membrane. It has not been decided whether these areas have a disc shape; their length measures between 0.04 and 0.47 µ. The five-layer pattern characteristic of an external compound membrane is shown in specimens fixed with formalin—OsO4, glutaraldehyde—acrolein—OsO4, and acrolein KMnO4 but it does not appear in the glutaraldehyde-OsO4-fixed specimens. The over-all thickness of the external compound membrane varies depending upon the fixative used. The synaptic clefts in the regions between the external compound membrane discs are widened and measure ∼300 A. A condensation of dense material occurs in pre- and postsynaptic cytoplasms all along the synaptic membrane complex. The morphological relationships described in the spoon endings are suggestive of electrical transmission.

Chromoplasts in Rosa rugosa: Development and Chemical Characterization of Tubular Elements

1976 ◽  
Vol 31 (7-8) ◽  
pp. 456-460d ◽  
Author(s):  
Hans-Gunter Wuttke
Keyword(s):  
Fine Structure ◽  
Chemical Composition ◽  
Cross Section ◽  
Early Stage ◽  
Chemical Characterization ◽  
Longitudinal Axis ◽  
Rosa Rugosa ◽  
Polarizing Microscopy ◽  
Oriented Parallel

Abstract 1. Development and fine structure of the chromoplasts in hips of Rosa rugosa have been in­ vestigated by electron and polarizing microscopy. 2. The chromoplasts develop from chloroplasts. During disorganization of the thylakoid system characteristic strutures become visible: ‘oblique’ grana, U-shaped thylakoids, and occassionally ‘thylakoid teeth’ as well as thylakoid anastomoses. - In this early stage, tubules appear in the plastid matrix. They are sometimes connected with membranes, especially with thylakoids. 3. In ripe hips the chromoplasts are packed with tubules. These chromoplast tubules, which attain lengths of up to at least 1.5 μm, are non-ramified and lie parallel to each other. Their diameter is variable, with a mean of 18 nm. They are polygonal in cross-section with electron-dense walls and electron-transparent cores. Association of ellipsoidal osmiophilic globules with the tubules can often be seen. Irregularly swollen remnants of former thylakoids are found in connection with these tubules. In spindle-shaped chromoplasts, the tubules are oriented parallel to the longitudinal axis. Positive birefringence and positive dichroism are observed. 4. The chemical composition of tubule fractions has been analyzed. The tubules contain appreciable amounts of carotenoids, phospho- and glycolipids, and proteins. 5. The origin and development of the tubules is discussed. It appears likely that reorganization of part of the thylakoid system and synthesis of carotenoids are involved in the formation of tubules. 6. The plastids in the yellow autumn leaves of Rosa rugosa contain globules but not tubules.

scholarly journals Taxonomy and phylogeny of the ascomycetous yeast genus Zygoascus, with proposal of Zygoascus meyerae sp. nov. and related anamorphic varieties

2005 ◽  
Vol 55 (3) ◽  
pp. 1353-1363 ◽  
Author(s):  
Maudy Th. Smith ◽  
V. Robert ◽  
G. A. Poot ◽  
Wendy Epping ◽  
A. W. A. M. de Cock
Keyword(s):  
Internal Transcribed Spacer ◽  
Phylogenetic Analyses ◽  
Large Subunit ◽  
Type Material ◽  
Rrna Gene ◽  
Yeast Genus ◽  
Ascomycetous Yeast ◽  
Dna Relatedness ◽  
Rapd Fingerprints ◽  
Physiological Characters

Physiological characters, mating compatibility, PCR-RAPD fingerprints, mol% G+C content, DNA–DNA relatedness, and large-subunit and internal transcribed spacer rRNA gene sequences of strains assigned to the genus Zygoascus were re-examined. On the basis of those data, and after phylogenetic analyses, an emendation of Zygoascus hellenicus (type material is a cross of CBS 6736T×CBS 5839T) is proposed, comprising two novel anamorphic varieties, Candida steatolytica var. steatolytica (CBS 6736T) and C. steatolytica var. inositophila (CBS 5839T). A novel teleomorphic species, Zygoascus meyerae sp. nov. (type material is a cross of CBS 4099T×CBS 7521T) is described, together with two novel anamorphic varieties corresponding to it, Candida hellenica var. hellenica (CBS 4099T) and C. hellenica var. acidophila (CBS 7115T).

scholarly journals CHROMATOPHORE DEVELOPMENT, PITS, AND OTHER FINE STRUCTURE IN THE RED ALGA, LOMENTARIA BAILEYANA (HARV.) FARLOW

1962 ◽  
Vol 12 (3) ◽  
pp. 553-569 ◽  
Author(s):  
G. Benjamin Bouck
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Higher Plants ◽  
Red Alga ◽  
Cellular Structures ◽  
Secretory Function ◽  
Thin Sections ◽  
Floridean Starch ◽  
Oriented Parallel

Thin sections of the red alga, Lomentaria baileyana, a tubular member of the Rhodymeniales, were examined after permanganate fixation and Araldite embedding. Many of the cellular structures in Lomentaria were found to be similar to analogous structures in animals and higher plants. However, in the walls between cells are modified areas generally known as pits which are unique to the higher orders of red algae (Florideae). In this study the pits were found to consist of a plug-like structure surrounded by an uninterrupted membrane apparently continuous with the plasma membrane. Examination of the chromatophore revealed a characteristic limiting membrane, a relatively sparse distribution of plates, no grana, and a single disc apparently oriented parallel to the limiting membrane. In addition to their origin from non-lamellate proplastids, chromatophores were found capable of division by simple constriction. Floridean starch grains were observed outside the chromatophore and the possibility of an association of the first formed grains with portions of the endoplasmic reticulum is considered. Gland cells seem to have a high proportion of Golgi components (dictyosomes), and are believed to have some kind of secretory function. Many of the Golgi vesicles seem to open on the wall and presumably discharge their contents.

Fine Structure of Platelet Interaction with a New Microcrystalline Collagen Preparation

1974 ◽  
Vol 32 ◽  
pp. 58-59
Author(s):  
W. H. Zucker ◽  
R. G. Mason
Keyword(s):  
Fine Structure ◽  
Platelet Aggregation ◽  
Hydrochloric Acid ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Hemostatic Agent ◽  
Native Collagen ◽  
Fibrillar Morphology ◽  
Clinical Interest ◽  
New Form

Platelet adhesion initiates platelet aggregation and is an important component of the hemostatic process. Since the development of a new form of collagen as a topical hemostatic agent is of both basic and clinical interest, an ultrastructural and hematologic study of the interaction of platelets with the microcrystalline collagen preparation was undertaken.In this study, whole blood anticoagulated with EDTA was used in order to inhibit aggregation and permit study of platelet adhesion to collagen as an isolated event. The microcrystalline collagen was prepared from bovine dermal corium; milling was with sharp blades. The preparation consists of partial hydrochloric acid amine collagen salts and retains much of the fibrillar morphology of native collagen.

Pituitary Follicular Cells: Their Origin, Possible Function and Fate

1974 ◽  
Vol 32 ◽  
pp. 34-35
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
G. Penz ◽  
C. Ezrin
Keyword(s):  
Fine Structure ◽  
Secretory Granules ◽  
Follicular Cells ◽  
Human Pituitary ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Junctional Complexes

Follicular structures, in the rat pituitary, composed of cells joined by junctional complexes and possessing few organelles and few, if any, secretory granules, were first described by Farquhar in 1957. Cells of the same description have since been observed in several species including man. The importance of these cells, however, remains obscure. While studying human pituitary glands, we have observed wide variations in the fine structure of follicular cells which may lead to a better understanding of their morphogenesis and significance.

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