scholarly journals An Electron-Microscope Study of Cell Deletion in the Anuran Tadpole Tail During Spontaneous Metamorphosis with Special Reference to Apoptosis of Striated Muscle Fibres

1974 ◽  
Vol 14 (3) ◽  
pp. 571-585 ◽  
Author(s):  
J. F. R.KERR ◽  
B. HARMON ◽  
J. SEARLE
Keyword(s):  
Cell Death ◽  
Striated Muscle ◽  
Morphological Changes ◽  
Light And Electron Microscopy ◽  
Epidermal Cells ◽  
Similar Process ◽  
Muscle Fibres ◽  
Tadpole Tail ◽  
Anuran Tadpole ◽  
Cell Deletion

The mechanism of cell deletion responsible for involution of the anuran tadpole tail during spontaneous metamorphosis was studied by light and electron microscopy, attention being focused on epidermis and striated muscle. The earliest indication of pending dissolution of epidermal cells was found to be aggregation of condensed chromatin beneath the nuclear envelope. This is followed by breaking up of the nucleus, and cytoplasmic condensation and budding with the production of a number of compact, membrane-bounded cell fragments with relatively well preserved organelles. These are then ingested and degraded by nearby viable cells, the majority by distinctive macrophage-like cells, which are scattered throughout the epidermis, and a few by epithelial cells. The morphological changes observed in the dying epidermal cells are the same as those described both in the ‘programmed cell death’ that plays an important role in the normal development of vertebrate embryos and in the type of cell death that has been shown to be involved in regulating the size of tissues in adult mammals under normal as well as pathological conditions; it has been suggested elsewhere that apoptosis might be a suitable name for the phenomenon. Deletion of striated muscle fibres in the tadpole tail is accomplished by a process that appears to be a modification of classical apoptosis, in which dilatation and confluence of elements of the sarcoplasmic reticulum lead to internal fragmentation, the usual surface budding presumably being precluded by the large volume and specialized structure of these cells. The early and late nuclear changes, and the apparent ultrastructural integrity of organelles in the membrane-bounded muscle fragments are typical of apoptosis, and subsequent degradation within macrophages follows the standard stereotyped pattern. An essentially similar process has been described by others in the muscles of metamorphosing insect larvae, but whether striated muscle cells in adult higher vertebrates can undergo apoptosis is still uncertain.

The structure of the antennal heart of Aedes aegypti (Linnaeus)

1997 ◽  
Vol 75 (3) ◽  
pp. 444-458 ◽  
Author(s):  
B. D. Sun ◽  
J. M. Schmidt
Keyword(s):  
Electron Microscopy ◽  
Connective Tissue ◽  
Aedes Aegypti ◽  
Light And Electron Microscopy ◽  
Single Layer ◽  
Epidermal Cells ◽  
Muscle Fibres ◽  
Columnar Cells

The structure of the antennal heart of Aedes aegypti (L.) (Diptera: Culicidae) was observed using light and electron microscopy. The antennal heart consists of several distinct regions including a single layer of columnar cells, the chamber walls, the valve, the z-body, the muscle fibres, and the connective tissue filaments. The columnar cells are structurally similar to secretory and osmoregulatory cells. Features of tendinous epidermal cells typically involved in the attachment of muscles to the cuticle can be observed in various areas of the antennal heart when it is examined as a whole. A model describing the pumping mechanism of the antennal heart in A. aegypti is presented.

Autolysis and heterolysis of the epidermal cells in anuran tadpole tail regression

1985 ◽  
Vol 185 (2) ◽  
pp. 269-275 ◽  
Author(s):  
Tsutomu Kinoshita ◽  
Fumie Sasaki ◽  
Kyozo Watanabe
Keyword(s):  
Epidermal Cells ◽  
Tadpole Tail ◽  
Anuran Tadpole

Internal morphology of the gill of a loricariid fish, Hypostomus plecostomus: arterio-arterial vasculature and muscle organization

1995 ◽  
Vol 73 (12) ◽  
pp. 2259-2265 ◽  
Author(s):  
M. N. Fernandes ◽  
S. A. Perna
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Striated Muscle ◽  
Light And Electron Microscopy ◽  
Muscle Cells ◽  
Muscle Fibres ◽  
Striated Muscles ◽  
Vascular Perfusion ◽  
Hypoxic Conditions ◽  
Adductor Muscles

The structural organization of the interbranchial septum of the gill arch of the air-breathing loricariid fish Hypostomus plecostomus was examined using light and electron microscopy. In the middle of the interbranchial septum, an extensive interconnection was found between the afferent primary arteries from successive and opposing primary lamellae. The blood circulates among numerous trabeculae consisting of connective tissue, smooth muscle cells, and collagen fibres. A sheet of smooth muscle cells is localized at the borders of these interconnected primary arteries and joins the cartilage rod from one primary lamella to the adjacent one on the same hemibranch. The adductor muscles are restricted to the distal end of the interbranchial septum and consist of transverse and oblique striated muscle fibres fixed to the cartilage rod from the primary lamella of opposite hemibranchs. The arrangement of these muscle fibres suggests a double movement of adduction: approximation of the tips of the primary lamellae of opposing hemibranchs and reduction of the space between adjacent primary lamellae of the same hemibranch. The action of both smooth and striated muscles reduces the interconnecting vascular septal space between the primary arteries, which may allow fine adjustment of vascular perfusion of the distal part of the filaments as an adaptation for better blood flow under hypoxic conditions.

scholarly journals Infection Behavior of Venturia nashicola, the Cause of Scab on Asian Pears

2000 ◽  
Vol 90 (11) ◽  
pp. 1209-1216 ◽  
Author(s):  
P. Park ◽  
H. Ishii ◽  
Y. Adachi ◽  
S. Kanematsu ◽  
H. Ieki ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Death ◽  
Light And Electron Microscopy ◽  
Fungal Growth ◽  
Resistance Mechanisms ◽  
Epidermal Cells ◽  
Japanese Pear ◽  
Fungal Cell ◽  
Mechanism Of Resistance ◽  
Venturia Nashicola

The infection of Japanese pear by Venturia nashicola, the cause of scab on Asian pears (Japanese pear, Pyrus pylifolia var. culta; Chinese pear, P. ussuriensis), was examined using light and electron microscopy to determine the mechanism of resistance in pears. Early stages of infection were similar on the susceptible cv. Kosui, the resistant cv. Kinchaku, and the nonhost European pear (P. communis) cv. Flemish Beauty. V. nashicola penetrated only the cuticle layer on pear leaves and formed subcuticular hyphae on all three cultivars. Hyphae were localized in the pectin layer of pear leaves and never penetrated into the cytoplasm of epidermal cells. This restriction of fungal growth suggested that pectinases released by infection hyphae or subcuticular hyphae may be important in infection. Subcuticular hyphae were modified ultrastructurally in the pectin layer of resistant pear cultivars accompanied by fungal cell death. In contrast, fungal cells appeared intact in susceptible pear cultivars, suggesting the existence of resistance mechanisms.

Oxidative Stress, Ocular Disease and Diabetes Retinopathy

2019 ◽  
Vol 24 (40) ◽  
pp. 4726-4741 ◽  
Author(s):  
Orathai Tangvarasittichai ◽  
Surapon Tangvarasittichai
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Cell Death ◽  
Protein Modification ◽  
Morphological Changes ◽  
Corneal Dystrophy ◽  
Age Related Macular Degeneration ◽  
Ocular Diseases ◽  
Retinal Light Damage ◽  
Age Related

Background: Oxidative stress is caused by free radicals or oxidant productions, including lipid peroxidation, protein modification, DNA damage and apoptosis or cell death and results in cellular degeneration and neurodegeneration from damage to macromolecules. Results: Accumulation of the DNA damage (8HOdG) products and the end products of LPO (including aldehyde, diene, triene conjugates and Schiff’s bases) were noted in the research studies. Significantly higher levels of these products in comparison with the controls were observed. Oxidative stress induced changes to ocular cells and tissues. Typical changes include ECM accumulation, cell dysfunction, cell death, advanced senescence, disarrangement or rearrangement of the cytoskeleton and released inflammatory cytokines. It is involved in ocular diseases, including keratoconus, Fuchs endothelial corneal dystrophy, and granular corneal dystrophy type 2, cataract, age-related macular degeneration, primary open-angle glaucoma, retinal light damage, and retinopathy of prematurity. These ocular diseases are the cause of irreversible blindness worldwide. Conclusions: Oxidative stress, inflammation and autophagy are implicated in biochemical and morphological changes in these ocular tissues. The development of therapy is a major target for the management care of these ocular diseases.

Linear electrical properties of striated muscle fibres observed with intracellular electrodes

1964 ◽  
Vol 160 (978) ◽  
pp. 69-123 ◽  
Keyword(s):  
Electrical Properties ◽  
Striated Muscle ◽  
Surface Membrane ◽  
Fibre Surface ◽  
Step Function ◽  
Muscle Fibres ◽  
Appreciable Effect ◽  
Current Application ◽  
Current Path ◽  
Wide Range

The linear electrical properties of muscle fibres have been examined using intracellular electrodes for a. c. measurements and analyzing observations on the basis of cable theory. The measurements have covered the frequency range 1 c/s to 10 kc/s. Comparison of the theory for the circular cylindrical fibre with that for the ideal, one-dimensional cable indicates that, under the conditions of the experiments, no serious error would be introduced in the analysis by the geometrical idealization. The impedance locus for frog sartorius and crayfish limb muscle fibres deviates over a wide range of frequencies from that expected for a simple model in which the current path between the inside and the outside of the fibre consists only of a resistance and a capacitance in parallel. A good fit of the experimental results on frog fibres is obtained if the inside-outside admittance is considered to contain, in addition to the parallel elements R m = 3100 Ωcm 2 and C m = 2.6 μF/cm 2 , another path composed of a resistance R e = 330 Ωcm 2 in series with a capacitance C e = 4.1 μF/cm 2 , all referred to unit area of fibre surface. The impedance behaviour of crayfish fibres can be described by a similar model, the corresponding values being R m = 680 Ωcm 2 , C m = 3.9 μF/cm 2 , R e = 35 Ωcm 2 , C e = 17 μF/cm 2 . The response of frog fibres to a step-function current (with the points of voltage recording and current application close together) has been analyzed in terms of the above two-time constant model, and it is shown that neglecting the series resistance would have an appreciable effect on the agreement between theory and experiment only at times less than the halftime of rise of the response. The elements R m and C m are presumed to represent properties of the surface membrane of the fibre. R e and C e are thought to arise not at the surface, but to be indicative of a separate current path from the myoplasm through an intracellular system of channels to the exterior. In the case of crayfish fibres, it is possible that R e (when referred to unit volume) would be a measure of the resistivity of the interior of the channels, and C e the capacitance across the walls of the channels. In the case of frog fibres, it is suggested that the elements R e , C e arise from the properties of adjacent membranes of the triads in the sarcoplasmic reticulum . The possibility is considered that the potential difference across the capacitance C e may control the initiation of contraction.

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