Changes in Structure of the Disks of Retinal Rods in Hypotonic Solutions

1973 ◽  
Vol 13 (3) ◽  
pp. 787-797
Author(s):  
GERTRUDE FALK ◽  
P. FATT
Keyword(s):  
Electron Microscopy ◽  
Cross Sections ◽  
Light And Electron Microscopy ◽  
Ringer Solution ◽  
Rod Outer Segments ◽  
Outer Segments ◽  
Retinal Rods

Changes in isolated frog rod outer segments, suspended in hypotonic solutions, have been examined by light and electron microscopy. Swelling of the disk occurs in hypotonic solutions. When one half or more NaCl is omitted from the Ringer solution used for suspending the rod outer segments, swelling is accompanied by the appearance of localized, irregular expansions projecting as buds from the disks. The axes of the buds tend to be in the plane of the disk, as can be seen in cross-sections of outer segments. In longitudinal sections of outer segments, the sectioned buds have profiles which were previously interpreted as vesicles. Attention is drawn to the properties of the disk edge, among which is a resistance to extension.

Electron Microscopy of Frog Photoreceptor Outer Segments after Fixation with Aldehydes

1974 ◽  
Vol 16 (1) ◽  
pp. 199-219
Author(s):  
G. J. JONES
Keyword(s):  
Electron Microscopy ◽  
Osmium Tetroxide ◽  
Ringer Solution ◽  
Rod Outer Segments ◽  
Buffer Concentration ◽  
Glutaraldehyde Fixation ◽  
Photoreceptor Outer Segments ◽  
Outer Segments ◽  
Cytoplasmic Material ◽  
Disk Membrane

The appearance of the outer segments of isolated retinae fixed with glutaraldehyde or formaldehyde alone, or with these aldehydes and postfixed with osmium tetroxide, is described. Rod outer segments and, to a lesser extent, cone outer segments of retinae fixed only with glutaraldehyde show shrinkage or swelling artifacts which are dependent on the fixative buffer concentration. The rod outer segments are most normal with a fixative phosphate buffer about 50% isotonic with retinal Ringer solution. The disks fixed with glutaraldehyde alone have a granular pentalaminar structure. At the edge of the rod disks, the loops formed by folding over of the disk membranes are seen after glutaraldehyde fixation alone to be filled with stainable material and the edges of adjacent loops to be in contact. The edge of the disk stack thus appears to be a more solid structure than previously thought, and it only partly survives osmium tetroxide treatment, even after glutaraldehyde fixation. Similarly, the arrangement of the disk membranes after glutaraldehyde fixation also appears to be weakened by postfixation with osmium tetroxide. For rod outer segments showing severe shrinkage after glutaraldehyde fixation alone, the interdisk clear spaces are lost and stainable cytoplasmic material, probably protein, is trapped between the disks. The disk membranes then appear as light lines on a dark background, since the central, unstained hydrophobic regions of each disk membrane become prominent.

Freeze-Fracture Replication of Frozen Outer Segments of Rat Retinal Rods

1969 ◽  
Vol 27 ◽  
pp. 392-393
Author(s):  
Thomas S. Leeson ◽  
C. Roland Leeson
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Outer Segment ◽  
Freeze Fracture ◽  
X Ray Diffraction ◽  
X Ray ◽  
Outer Segments ◽  
Retinal Rods ◽  
Temperature Electron ◽  
Freeze Etching

Numerous previous studies of outer segments of retinal receptors have demonstrated a complex internal structure of a series of transversely orientated membranous lamellae, discs, or saccules. In cones, these lamellae probably are invaginations of the covering plasma membrane. In rods, however, they appear to be isolated and separate discs although some authors report interconnections and some continuities with the surface near the base of the outer segment, i.e. toward the inner segment. In some species, variations have been reported, such as longitudinally orientated lamellae and lamellar whorls. In cross section, the discs or saccules show one or more incisures. The saccules probably contain photolabile pigment, with resulting potentials after dipole formation during bleaching of pigment. Continuity between the lamina of rod saccules and extracellular space may be necessary for the detection of dipoles, although such continuity usually is not found by electron microscopy. Particles on the membranes have been found by low angle X-ray diffraction, by low temperature electron microscopy and by freeze-etching techniques.

The Response of Testis Cells to Low Dose X-Irradiation

1981 ◽  
Vol 39 ◽  
pp. 542-543
Author(s):  
D. E. Philpott ◽  
W. Sapp ◽  
C. Williams ◽  
Joann Stevenson ◽  
S. Black
Keyword(s):  
Electron Microscopy ◽  
Stem Cell ◽  
Light Microscopy ◽  
Dose Level ◽  
Cross Sections ◽  
Low Dose ◽  
Light And Electron Microscopy ◽  
Cellular Responses ◽  
Post Irradiation ◽  
X Irradiation

The response of spermatogonial cells to X-irradiation is well documented. It has been shown that there is a radiation resistent stem cell (As) which, after irradiation, replenishes the seminiferous epithelium. Most investigations in this area have dealt with radiation dosages of 100R or more. This study was undertaken to observe cellular responses at doses less than 100R of X-irradiation utilizing a system in which the tissue can be used for light and electron microscopy.Brown B6D2F1 mice aged 16 weeks were exposed to X-irradiation (225KeV; 15mA; filter 0.35 Cu; 50-60 R/min). Four mice were irradiated at each dose level between 1 and 100 rads. Testes were removed 3 days post-irradiation, fixed, and embedded. Sections were cut at 2 microns for light microscopy. After staining, surviving spermatogonia were identified and counted in tubule cross sections. The surviving fraction of spermatogonia compared to control, S/S0, was plotted against dose to give the curve shown in Fig. 1.

scholarly journals INHERITED RETINAL DYSTROPHY IN THE RAT

1962 ◽  
Vol 14 (1) ◽  
pp. 73-109 ◽  
Author(s):  
John E. Dowling ◽  
Richard L. Sidman
Keyword(s):  
Pigment Epithelium ◽  
Light And Electron Microscopy ◽  
Retinal Dystrophy ◽  
Photoreceptor Cells ◽  
Pigment Cells ◽  
Membrane Thickness ◽  
Outer Segments ◽  
Progressive Loss ◽  
Retinal Rods ◽  
Microscopy Data

Retinal dystrophies, known in man, dog, mouse, and rat, involve progressive loss of photoreceptor cells with onset during or soon after the developmental period. Functional (electroretinogram), chemical (rhodopsin analyses) and morphological (light and electron microscopy) data obtained in the rat indicated two main processes: (a) overproduction of rhodopsin and an associated abnormal lamellar tissue component, (b) progressive loss of photoreceptor cells. The first abnormality recognized was the appearance of swirling sheets or bundles of extracellular lamellae between normally developing retinal rods and pigment epithelium; membrane thickness and spacing resembled that in normal outer segments. Rhodopsin content reached twice normal values, was present in both rods and extracellular lamellae, and was qualitatively normal, judged by absorption maximum and products of bleaching. Photoreceptors attained virtually adult form and ERG function. Then rod inner segments and nuclei began degenerating; the ERG lost sensitivity and showed selective depression of the a-wave at high luminances. Outer segments and lamellae gradually degenerated and rhodopsin content decreased. No phagocytosis was seen, though pigment cells partially dedifferentiated and many migrated through the outer segment-debris zone toward the retina. Eventually photoreceptor cells and the b-wave of the ERG entirely disappeared. Rats kept in darkness retained electrical activity, rhodopsin content, rod structure, and extracellular lamellae longer than litter mates in light.

scholarly journals THE STRUCTURE AND CONCENTRATION OF SOLIDS IN PHOTORECEPTOR CELLS STUDIED BY REFRACTOMETRY AND INTERFERENCE MICROSCOPY

1957 ◽  
Vol 3 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Richard L. Sidman
Keyword(s):  
Photoreceptor Cells ◽  
Interference Microscopy ◽  
Refractive Indices ◽  
Rod Outer Segments ◽  
Vertebrate Species ◽  
Rods And Cones ◽  
Outer Segments ◽  
Retinal Rods ◽  
Cone Cells ◽  
Longitudinal Fiber

Fragments of freshly obtained retinas of several vertebrate species were studied by refractometry, with reference to the structure of the rods and cones. The findings allowed a reassessment of previous descriptions based mainly on fixed material. The refractometric method was used also to measure the refractice indices and to calculate the concentrations of solids and water in the various cell segments. The main quantitative data were confirmed by interference microscopy. When examined by the method of refractometry the outer segments of freshly prepared retinal rods appear homogeneous. Within a few minutes a single eccentric longitudinal fiber appears, and transverse striations may develop. These changes are attributed to imbibition of water and swelling in structures normally too small for detection by light microscopy. The central "core" of outer segments and the chromophobic disc between outer and inner segments appear to be artifacts resulting from shrinkage during dehydration. The fresh outer segments of cones, and the inner segments of rods and cones also are described and illustrated. The volumes, refractive indices, concentrations of solids, and wet and dry weights of various segments of the photoreceptor cells were tabulated. Rod outer segments of the different species vary more than 100-fold in volume and mass but all have concentrations of solids of 40 to 43 per cent. Cone outer segments contain only about 30 per cent solids. The myoids, paraboloids, and ellipsoids of the inner segments likewise have characteristic refractive indices and concentrations of solids. Some of the limitations and particular virtues of refractometry as a method for quantitative analysis of living cells are discussed in comparison with more conventional biochemical techniques. Also the shapes and refractive indices of the various segments of photoreceptor cells are considered in relation to the absorption and transmission of light. The Stiles-Crawford effect can be accounted for on the basis of the structure of cone cells.

Analysis of the defects occurrence on the functional surfaces of individual mould segments for the tyre production from AlSi7Mg0.3Sr

2020 ◽  
Vol 234 (17) ◽  
pp. 3474-3483 ◽  
Author(s):  
I Hren ◽  
S Michna ◽  
J Svobodova ◽  
L Michnova ◽  
L Benes
Keyword(s):  
Electron Microscopy ◽  
Cross Sections ◽  
Surface Defects ◽  
Subsurface Layer ◽  
Light And Electron Microscopy ◽  
Microstructural Characterization ◽  
Casting Process ◽  
Functional Surface ◽  
X Ray ◽  
Functional Surfaces

The basic prerequisite for obtaining a quality casting according to the requirements and specifics of the customer is the production of the mould (in our case using low-pressure die-casting) without the occurrence of surface defects in the form of cracks, scabs, microshrinkages and local depressions. In this case, the mould segments for the tyre production are those which show tiny cracks or scabs on the functional surface of the castings that define the surface quality of the resulting product. It is necessary to analyse these defects in order to eliminate the causes of their formation in the casting process. For this reason, a new alloy of eutectic silumin AlSi9 alloyed with Mg, Mn and modified Sr was prepared in order to improve the fluidity and maintain the mechanical properties of the material up to 250 ℃ The subject of the study was the analysis of the surface defects of the mould, including the analysis of the chemical composition (energy-dispersive X-ray) and microstructure in the defect area. In order to investigate the subsurface layer of defects, metallographic specimens of cross-sections were prepared by means of mould, which were examined by light and electron microscopy. The detailed microstructural characterization of individual elements was performed on lamellas of the mould studied using transmission electron microscopy. An X-ray diffraction analysis was performed to investigate the residual stress at the defects area very closely. It has been found that a smaller number of defects on the functional surfaces can be obtained by changing the mould position during casting.

scholarly journals Microstructure of Soft Scald in ‘Honeycrisp’ Apples

2017 ◽  
Vol 142 (6) ◽  
pp. 464-469
Author(s):  
Yin Xu ◽  
Yizhou Ma ◽  
Nicholas P. Howard ◽  
Changbin Chen ◽  
Cindy B.S. Tong ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cross Sections ◽  
Light And Electron Microscopy ◽  
Breeding Population ◽  
Epidermal Cells ◽  
Fruit Peel ◽  
Cellular Microstructure ◽  
Apple Cultivars ◽  
Honeycrisp Apples ◽  
Soft Scald

Soft scald is an apple (Malus ×domestica Borkh.) fruit disorder that appears in response to cold storage after about 2–8 weeks. It appears as a ribbon of dark tissue on the peel of the fruit, with occasional browning into the flesh. Several apple cultivars are susceptible to it, including Honeycrisp. The objectives of this study were to examine the cellular microstructure of fruit exhibiting soft scald and determine if any aspect of the peel microstructure at harvest could be indicative of future soft scald incidence. Light and electron microscopy were used to examine the peel microstructure of ‘Honeycrisp’ fruit that were unaffected or affected by soft scald. Tissue with soft scald had brown pigmented epidermal and hypodermal cells, whereas unaffected fruit peel epidermal cells were unpigmented. Cuticular wax of unaffected peel had upright wax platelets or clumps of wax, but peel surfaces with soft scald exhibited flattened granules and were more fragile than that of unaffected fruit. Epidermal cells of fruit with soft scald were more disorganized than that of unaffected fruit. Light microscopy was used to examine peels of ‘Honeycrisp’ fruit from four growing locations and fruit from a ‘Honeycrisp’ breeding population at harvest. ‘Honeycrisp’ and ‘Honeycrisp’ progeny fruit were also stored at 0 °C for 8 weeks and scored for soft scald incidence. Cross-sections of unaffected peel of stored ‘Honeycrisp’ fruit looked similar to that of freshly harvested fruit. No significant correlations were found between soft scald incidence and measured microstructural attributes of ‘Honeycrisp’ fruit at harvest, suggesting that peel microstructure cannot be used to predict possible soft scald incidence after storage.

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 Cone outer segment morphogenesis: taper change and distal invaginations.

1987 ◽  
Vol 105 (5) ◽  
pp. 2267-2277 ◽  
Author(s):  
M S Eckmiller
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Outer Segment ◽  
Shape Change ◽  
Light And Electron Microscopy ◽  
Vertebrate Species ◽  
Ultrastructural Examination ◽  
Noticeable Change ◽  
Outer Segments

Because cone outer segments (COS) are now known to be continually renewed, I reexamined COS morphogenesis in retinas of Xenopus tadpoles (prepared by standard histologic techniques and viewed by light and electron microscopy) to clarify how COS incorporate new membrane. I observed that developing COS underwent an unexpected shape change: they were always conical, but their taper (width divided by length) continually decreased. Ultrastructural examination revealed that many of the membrane foldings within distal COS were partial or incomplete, not extending across the full COS width but ending at variable distances from the ciliary side. Because these partial folds represented infoldings of the plasma membrane of an existing lamella, and they occurred at all COS levels except the base, I have termed them distal invaginations (DI). The completion of each DI increased COS length by one lamella but caused no noticeable change in local COS width; thus the formation of many DI throughout the distal COS presumably resulted in the observed decrease in overall COS taper. Based on these findings, I suggest that DI indicate growing membrane fronts and may represent sites where newly synthesized membrane is incorporated into COS. Because DI occur in developing and adult COS of various vertebrate species, I propose that DI formation plays an important role in the generation of COS taper during development and the remodeling of COS taper in mature cones after tip shedding.

Appearance of cGMP-phosphodiesterase immunoreactivity parallels the morphological differentiation of photoreceptor outer segments in the rat retina

1993 ◽  
Vol 10 (3) ◽  
pp. 395-402 ◽  
Author(s):  
Laura Colombaioni ◽  
Enrica Strettoi
Keyword(s):  
Electron Microscopy ◽  
Postnatal Development ◽  
Morphological Differentiation ◽  
Specific Marker ◽  
Rod Outer Segments ◽  
Sudden Increase ◽  
Rat Retina ◽  
Photoreceptor Outer Segments ◽  
Outer Segments ◽  
Temporally Correlated

AbstractWe have investigated by immunofluorescence the appearance of immunoreactive guanosine 3′-5′ cyclic monophosphate phosphodiesterase (cGMP-PDE) during the postnatal development of the retina of the pigmented rat. We show that a sudden increase in immunoreactivity takes place during postnatal day five (P5), when rod outer segments begin to form; immunoreactivity develops rapidly in the following days. Labeling is restricted to the developing photoreceptor outer segments, sparing other retinal cells, as confirmed by electron microscopy immunocytochemistry. In addition, cGMP-PDE immunoreactivity follows a center-to-periphery gradient paralleling photoreceptor differentiation. It appears that cGMP-PDE is expressed when the photoreceptor subcellular compartments are already formed, and represents a specific marker of late photoreceptor differentiation. The appearance of cGMP-PDE during development is temporally correlated with the appearance of other proteins of the phototransduction machinery.

Sign in / Sign up

Export Citation Format

Share Document