scholarly journals The Fine Structure of the Retina Studied with the Electron Microscope

1959 ◽  
Vol 6 (2) ◽  
pp. 225-230 ◽  
Author(s):  
Kiyoteru Tokuyasu ◽  
Eichi Yamada
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Electron Microscope ◽  
Outer Segment ◽  
Distal Region ◽  
Serial Sections ◽  
Tubular Structures ◽  
Detailed Structure ◽  
Subsequent Time ◽  
Retinal Rods

The morphogenesis of the outer segments of retinal rods was studied mainly in the kitten before the opening of the eye, and the probable sequence of the morphogenetic stages is deduced. Since the development of retinal rods is not synchronous, the deductions were based on observations of many single and serial sections. One centriole extends ciliary tubules of about 0.5 µ long, in the growing primitive cilium. Beyond this length, each ciliary tubule becomes a row of small vesicles (called "ciliary vesicles" in this paper), which penetrate into the distal region of the cilium. Where the ciliary vesicles establish contact with the plasma membrane of the distal region of the cilium, more or less deep infoldings of the plasma membrane are observed. In the distal region can be seen rows of tubular or vesicular structures. A few of these membranous structures are continuous with the bottoms of the infoldings. At the following stage, the infoldings disappear and the ciliary vesicles lose contact with the distal plasma membrane. Nonetheless, the formation of the tubular structures continues in the distal region of the primitive outer segment. The tubular structures appear to be transformed into the primitive rod sacs by sidewise enlargement. At a subsequent time, presumably, these primitive rod sacs flatten and are rearranged into a position perpendicular to the long axis of the outer segment. The detailed structure of the basal body of the connecting cilium was also studied by means of serial sections.

scholarly journals The Fine Structure of a Multiterminal Innervation of an Insect Muscle

1959 ◽  
Vol 5 (2) ◽  
pp. 241-244 ◽  
Author(s):  
George A. Edwards
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Electron Microscope ◽  
Basement Membrane ◽  
Neuromuscular Junctions ◽  
Abdominal Muscle ◽  
Membrane Material ◽  
Detailed Structure ◽  
Insect Muscle

The detailed structure of nerve branches, neuromuscular junctions, and muscle fibers of a multiterminal innervation of cockroach abdominal muscle has been studied with the electron microscope. The muscle fiber is of the banded myofibril type; with paired mitochondria and abundant endoplasmic reticulum. The peripheral nerve branches are multiaxonal with large central axon and several small peripheral tunicated axons. Tracheoblasts closely accompany the nerve branches. The multiple neuromuscular junctions show typical axonal vesicles, muscle aposynaptic granules, and close plasma membrane apposition with no interposition of basement membrane material.

Rod and cone-type photoreceptors in the post-equatorial region of the albino rat retina: a morphometric analysis of their incidence and fine structure

1978 ◽  
Vol 36 (2) ◽  
pp. 610-611
Author(s):  
K. M. Jonson ◽  
R. A. Champion ◽  
C. D. Shorey ◽  
P. E. Beaumont
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Outer Segment ◽  
Receptor Cell ◽  
Equatorial Region ◽  
Albino Rat ◽  
Rat Retina ◽  
Photoreceptor Layer ◽  
Cone Type ◽  
Type Receptor

The existence of cones in the rat retina is controversial. Although the rat has been thought to possess an exclusive rod retina (Lashley, 1932; Detwiler, 1943), Walls (1934) reported the existence of “typical cones” essentially similar to those of the primate. More recent light and electron microscope studies have also reported on the presence of cones in the rat retina (Leure-duPree, 1974; LaVail, 1976). A quantitative analysis of their incidence and fine structure has not previously been reported.The results of the present investigation demonstrate that although the rat photoreceptor layer is rod-dominant, approximately 17% of its cells would, on morphological grounds, qualify as “cone-type” receptors. These, however, are not typical cones, as their inner and outer segments do not show the characteristic conical taper and appear morphologically similar to the slender cylindrical-shaped rod inner and outer segment. Apart from this, the rat cone-type receptor cell does resemble the cone typically observed in other species.

scholarly journals Electron Microscopy of Retinal Photoreceptors

1960 ◽  
Vol 7 (3) ◽  
pp. 493-497 ◽  
Author(s):  
Arnaldo Lasansky ◽  
Eduardo de Robertis
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Electron Microscope ◽  
Outer Segment ◽  
Osmium Tetroxide ◽  
The Other ◽  
Rod Outer Segments ◽  
Outer Segments ◽  
Retinal Photoreceptors ◽  
L1 And L2

The fine structure of the cone and rod outer segments of the toad was studied under the electron microscope after fixation in osmium tetroxide and fixation in formaldehyde followed by chromation. In the OsO4-fixed specimens, the rod outer segment appears to be built of a stack of lobulated flattened sacs, each of which is made of two membranes of about 40 A separated by an innerspace of about 30 A. The distance between the rod sacs is about 50 A. The sacs in the cone outer segment are originated by the folding of a continuous membrane. The thickness of the membranes and width of the spaces between the cone sacs is the same as in rod, but the sac innerspace is slightly narrower in the cone (∼ 20 A). After fixation in formaldehyde and chromation, two different dense lines (l1 and l2) separated by spaces of less density appear. One of the lines, l1, has a thickness of 70 A and is less dense than the other, l2, which is 30 A thick. The correlation of the patterns obtained with both fixatives is considered and two possible interpretations are given. The possibility that l2 is related to a soluble phospholipid component is discussed. It is suggested that the outer segments have a paracrystallin organization similar to that found in myelin.

scholarly journals THE FINE STRUCTURE OF THE MID-BODY OF THE RAT ERYTHROBLAST

1962 ◽  
Vol 13 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Robert C. Buck ◽  
James M. Tisdale
Keyword(s):  
Bone Marrow ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cleavage Furrow ◽  
Intercellular Bridge ◽  
Spindle Fiber ◽  
Thin Sections ◽  
Rat Bone ◽  
Spindle Fibers

The development of the mid-body has been studied in mitotic erythroblasts of the rat bone marrow by means of thin sections examined with the electron microscope. A differentiated region on the continuous spindle fibers, consisting of a localized increase in density, is observed at the equatorial plane. The mid-body seems to develop by the aggregation of such denser lengths of spindle fiber. Its appearance precedes that of the cleavage furrow. A plate-like arrangement of fibrillary material lies transversely across the telophase intercellular bridge. Later, this material becomes amorphous and assumes the form of a dense ring closely applied to a ridge in the plasma membrane encircling the middle of the bridge. Although the mid-body forms in association with the spindle fibers, it is a structurally distinct part, and the changes which it undergoes are not shared by the rest of the bundle of continuous fibers.

scholarly journals THE FINE STRUCTURE OF CHONDROCOCCUS COLUMNARIS

1967 ◽  
Vol 35 (1) ◽  
pp. 15-35 ◽  
Author(s):  
Jack L. Pate ◽  
John L. Johnson ◽  
Erling J. Ordal
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
The Other ◽  
Tubular Structures ◽  
Axial Hole

When cells of C. columnaris were broken open, treated with PTA, and examined in the electron microscope, tubular structures (rhapidosomes) were present in the preparations. The rhapidosomes are approximately 300 A in diameter. Their length varies from about 500 to about 15,000 A. An axial hole which runs the length of the rhapidosomes appears to widen and narrow with a regular periodicity. End-on views of short segments of rhapidosomes revealed the presence of subunits around their outside peripheries. The results of studies of lysed cells and of sectioned cells indicate that the rhapidosomes are produced during the disintegration of cells. It seems likely that the compound membranes of the mesosomes break down to give rise to the tubular structures. The mesosomal origin of rhapidosomes is postulated only for the rhapidosomes of C. columnaris, since the origin of rhapidosomes from other organisms was not investigated during this study. The rhapidosomes of C. columnaris may be unrelated to those of S. grandis, S. myxococcoides, A. violaceum, and Sorangium 495, since there was a difference in the details of fine structure between rhapidosomes from C. columnaris and those found in the other four organisms.

scholarly journals FINE STRUCTURE OF THE LARVAL ANURAN EPIDERMIS, WITH SPECIAL REFERENCE TO THE FIGURES OF EBERTH

1961 ◽  
Vol 10 (3) ◽  
pp. 425-435 ◽  
Author(s):  
George B. Chapman ◽  
Alden B. Dawson
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Free Surface ◽  
Electron Microscope ◽  
Fibrous Material ◽  
Distal Region ◽  
Epidermal Layer ◽  
Basal Plasma Membrane ◽  
Basal Plasma ◽  
Ultrathin Sections

Small pieces of skin from 8 cm long Rana clamitans larvae were fixed in OsO4, washed, dehydrated, and embedded in a methacrylate mixture. Ultrathin sections were cut on a Porter-Blum ultramicrotome and were examined in an RCA electron microscope, type EMU 2D. The sections showed that aggregates of fibrous material in the cells of the inner layer of epidermal cells are identical in disposition and size with the classical figures of Eberth. It is conclusively shown that these figures do not arise from an aggregation of mitochondrial filaments. The tendency of the fibrils to concentrate on attachment points, or thickenings of the basal plasma membrane, is noted. It is also observed that numerous mitochondria are located in the distal region of the cells of the outer layer of epidermis in association with the secretory vacuoles. Microvilli are seen occasionally on the free surface of the skin. Cisternae are found only in the cells of the outer epidermal layer, while vesicular endoplasmic reticulum is found in the cells of both epidermal layers.

scholarly journals The Fine Structure of Streptomyces coelicolor

1960 ◽  
Vol 7 (3) ◽  
pp. 479-487 ◽  
Author(s):  
Audrey M. Glauert ◽  
David A. Hopwood
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Streptomyces Coelicolor ◽  
Nuclear Material ◽  
Tubular Structures ◽  
Thin Sections ◽  
Cytoplasmic Structure ◽  
Intracytoplasmic Membranes ◽  
Membranous Component

Colonies and spore suspensions of Streptomyces coelicolor were fixed by the method of Kellenberger, Ryter, and Séchaud (1958) and embedded in methacrylate or araldite. Thin sections were cut with an A. F. Huxley microtome and examined in a Siemens' Elmiskop I. At all stages of development the hyphae of Streptomyces coelicolor have an extensive membranous component in the cytoplasm. The membranes are continuous with the plasma membrane and have a variety of configurations at different places in the hyphae. Tubular structures, vesicles, and parallel stacks of membranes are seen. In some areas concentric layers of membranes form whorled structures which are particularly frequent in the region of developing cross-walls and within maturing spores. In the spores membranous structures often lie embedded in the nuclear material. In disintegrating hyphae the intracytoplasmic membranes round off into small vesicles and remain when the rest of the cytoplasmic structure has gone. In the absence of typical mitochondria and other cytoplasmic membranous structures it is possible that the membranous component of the cytoplasm of Streptomyces coelicolor may perform the functions of the endoplasmic reticulum and/or the mitochondria of higher cells.

scholarly journals Some Observations on the Fine Structure of the Giant Nerve Fibers of the Earthworm, Eisenia foetida

1959 ◽  
Vol 6 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Kiyoshi Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Schwann Cell ◽  
Plasma Membranes ◽  
Giant Axon ◽  
Nerve Fibers ◽  
Eisenia Foetida ◽  
Tubular Structures ◽  
Giant Fiber ◽  
Nerve Sheath

Sectioned dorsal giant fibers of the earthworm Eisenia foetida have been studied with the electron microscope. The giant axon is surrounded by a Schwannian sheath in which the lamellae are arranged spirally. They can be traced from the outer surface of the Schwann cell to the axon-Schwann membranes. Irregularities in the spiral arrangement are frequently observed. Desmosome-like attachment areas occur on the giant fiber nerve sheath. These structures appear to be arranged bilaterally in columns which are oriented slightly obliquely to the long axis of the giant fiber and aligned linearly from the axon to the periphery of the sheath. At these sites they bind together apposing portions of Schwann cell membrane comprising the sheath. Longitudinal or oblique sections of the nerve sheath attachment areas are reminiscent of the Schmidt-Lantermann clefts of vertebrate peripheral nerve. Septa of the giant fibers have been examined. They are symmetrical or non-polarized and consist of the two plasma membranes of adjacent nerve units. Characteristic vesicular and tubular structures are associated with both cytoplasmic surfaces of these septa.

scholarly journals THE FINE STRUCTURE OF CHONDROCOCCUS COLUMNARIS

1967 ◽  
Vol 35 (1) ◽  
pp. 37-51 ◽  
Author(s):  
Jack L. Pate ◽  
Erling J. Ordal
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Electron Microscope ◽  
Outer Membrane ◽  
Electron Microscope Study ◽  
Ruthenium Red ◽  
Gliding Motility ◽  
Dense Layer ◽  
Adhesive Properties

An electron microscope study of the myxobacterium Chondrococcus columnaris has revealed the following structures in the peripheral layers of the cells: (1) a plasma membrane, (2) a single dense layer (probably the mucopeptide component of the cell wall), (3) peripheral fibrils, (4) an outer membrane, and (5) a material coating the surfaces of the cells which could be stained with the dye ruthenium red.The ruthenium red-positive material is probably an acid mucopolysaccharide and may be involved in the adhesive properties of the cells. The outer membrane and plasma membrane both have the appearance of unit membranes: an electron-translucent layer sandwiched between two electron-opaque layers. The peripheral fibrils span the gap between the outer membrane and the mucopeptide layer, a distance of about 100 A, and run parallel to each other along the length of the cell. The fibrils appear to be continuous across the ends of the cells. The location of these fibrillar structures suggests that they may play a role in the gliding motility of these bacteria.

scholarly journals LE COMPLEXE MEMBRANAIRE SUPERFICIEL ET SON EVOLUTION LORS DE L'ELABORATION DES INDIVIDUS-FILS CHEZ TOXOPLASMA GONDII

1969 ◽  
Vol 43 (2) ◽  
pp. 329-342 ◽  
Author(s):  
Emile Vivier ◽  
André Petitprez
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Electron Microscope ◽  
Toxoplasma Gondii ◽  
Outer Membrane ◽  
Molecular Architecture ◽  
Daughter Cells ◽  
Membrane Complex ◽  
Local Differentiation

The parasitic protozoan Toxoplasma gondii has been examined with the electron microscope in order to study the fine structure and the formation of the membranes surrounding the cell. The study of the ultrastructure of the membranes covering the parasite shows the existence of a three-membraned complex. Only the outer membrane is considered to be the plasma membrane; the two membranes below it form an inseparable whole of changeable molecular architecture (modifications in appearance depending on the methods of fixation, local differentiation). During reproduction, which takes place by fission or more often by endogeny, the membranes of the daughter individuals are formed from the membranes of the parent. At first the middle and inner membranes of the parent extend, separating the cytoplasm of the daughter cells from that of the parent. The three-membrane complex of the endozoites is completed at the time of their liberation; the external membrane of the parent covers the leaving endozoites; thus, the plasma membrane of the daughter cells derives also from that of the parent. These findings on the origin and role of limiting membranes during reproduction differ entirely from those described so far for other cells.

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