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PubMed1991

Characterization of the functional stages of osteoclasts by enzyme histochemistry and electron microscopy.

To investigate the functional stages of osteoclasts, the ultrastructural histochemical distribution of the lysosomal enzymes [acid phosphatase (tartrate-sensitive) and neutral phosphatase], the plasma membrane enzymes [alkaline phosphatase, Ca(++)-ATPase, and alkaline ouabain-insensitive p-nitrophenylphosphatase (alkaline p-NPPase)], and the mitochondrial enzyme (cytochrome C oxidase) was evaluated in the chicken tibial metaphysis. Both active-appearing and detached (resting) osteoclasts were studied. Serial sectioning was used to identify detached osteoclasts which were present in the perivascular space. The ultrastructure of detached osteoclasts was similar to that of active osteoclasts, except for the lack of a ruffled border and clear zone, and an altered distribution pattern of small vesicles. Small vesicles were uniformly distributed in the cytoplasm of resting osteoclasts, whereas they were concentrated beneath the ruffled border of active osteoclasts. Alkaline p-NPPase, a marker enzyme for the basal ruffled border, was also apparent on the membrane of small vesicles. However, the vesicles did not possess Ca(++)-ATPase, a marker enzyme for the apical plasma membrane. These findings support the concept that small vesicles serve as a membrane reservoir for the ruffled border membrane. Pre-osteoclasts contained abundant mitochondria and lysosomes, prominent Golgi complexes, moderately developed endoplasmic reticulum, and lacked small vesicles. Pre-osteoclasts appear to fuse with osteoclasts which are attached to the bone surface, but not with detached osteoclasts. The small vesicles, from which the ruffled border arises, are absent from pre-osteoclasts, suggesting that they develop after fusion with pre-existing osteoclasts or after attachment to the bone surface. Alkaline p-NPPase appears to be a marker for differentiation of pre-osteoclasts to mature osteoclasts.

Animals↗
PubMed1987

Cytochrome oxidase activity in the rat caudate nucleus: light and electron microscopic observations.

Cytochrome oxidase (CO) activity was examined in the neostriatum of normal adult rats at the light and electron microscopic level. At the light microscopic level a heterogeneous distribution of CO activity was observed and was characterized by patches of high activity ranging in size from 200 to 800 microns surrounded or adjacent to regions of lower activity. The most dorsomedial and ventromedial regions of the caudate nucleus appeared to be consistently high in activity in all animals. At the ultrastructural level CO reaction product was localized to the membranes and intracristal spaces of mitochondria. The most reactive mitochondria (those containing the denest precipitates of reaction product) were found within the dendrites of spiny neurons in all caudate regions. In areas of high CO activity the mitochondria within bundles of myelinated fibers and in many axon terminals were also highly reactive whereas those in neuronal somata, primary dendrites, and glial cells and processes exhibited relatively little activity. Quantitative study showed that mitochondria within dendrites accounted for most of the CO activity in caudate neuropil. The mitochondria within dendrites and axon terminals were more reactive in regions of high CO activity than in regions of low CO activity. No differences in the density of synapses or in the proportions of axospinous and axodendritic synapses were observed between CO-rich and CO-poor areas. Heterogeneity in the distribution of CO activity in the caudate nucleus may be related to the "patchy" pattern of localization previously observed for some neostriatal afferents, enzymes, transmitters, peptides, and receptor ligands.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Laminar and sublaminar ultracytochemical localization of cytochrome oxidase in the optic tectum of normal goldfish.

Distinct laminae and sublaminae in the goldfish optic tectum exhibit substantial differences in cytochrome oxidase (C.O.) reactivity. To determine whether these differences are associated with differential reactivity of different neuronal profiles, each tectal sublamina was examined at the ultrastructural level following C.O. treatment. The greatest abundance of darkly reactive mitochondria was found in the optically innervated layers within both pre- and postsynaptic profiles in correspondence with the most intense staining of these layers at the light microscopic level. Many reactive mitochondria were localized within terminals that were presumed to be optic on the basis of cytological criteria or were shown to be optic by filling optic fibers with HRP and processing so as to simultaneously demonstrate both mitochondrial C.O. reactivity and HRP labeling. These optic terminals tended to differ from each other in size and level of reactivity. The largest terminals were located within sublamina d of the stratum fibrosum et griseum superficials (SFGSd), and these were the most intensely reactive and contained the greatest number of darkly reactive mitochondria. Medium-sized terminals were found within sublaminae SFGSa, SFGSb, and a and c of the stratum album centrale (SACa,c). These were also darkly reactive but contained fewer mitochondria. Other medium-to-small optic terminals were found in stratum opticum a and b (60a,b), SFGSb, SFGSc, and stratum griseum centrale c (SGCc). These typically contained fewer mitochondria that also tended to be relatively less reactive, although darkly reactive mitochondria were also present. We suggest that the metalbolic differences within optic terminals of different size and sublaminar stratification arise from different ganglion cell classes and that the different optic layers of tectum are functionally substratified. As expected, darkly reactive mitochondria were most abundant in th intensely stained sublaminae, which included the optic lamina SFGS and nonoptic sublamina SGCa, and they were found not only within optic terminals but also within dendrites, presynaptic dendrites, and nonoptic terminals as well. Glial processes tended to contain less reactive mitochondria. The most prominent of the nonoptic terminals were the large-diameter P1 terminals, which contained pleomorphic vesicles and formed symmetric (presumed inhibitory) synapses. In stratum marginale most of the darkly reactive mitochondria were localized within dendrites. In the rest of the tectal layers most of the darkly reactive mitochondria were found in both presynaptic terminals and dendrites.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Laminar histochemical and cytochemical localization of cytochrome oxidase in the goldfish retina and optic tectum in response to deafferentation and during regeneration.

Cytochrome oxidase (C.O.) histochemistry and cytochemistry were used to examine the effects of optic denervation and subsequent optic fiber regeneration on oxidative metabolism in the retina and optic tectum of the goldfish. In the tectum, there was a dramatic and rapid decrease in C.O. activity within the optic layers 3-4 days after contralateral eye removal or optic nerve crush. At the E.M. level this was correlated with an initial decrease in mitochondrial reactivity within optic terminals followed by the subsequent degradation of mitochondria and phagocytosis of optic terminals. By 1 month after optic nerve crush, the entire tectum was reinnervated. However, the normal dark reactivity of the stratum fibrosum et griseum superficialis (SFGS), the main optic innervation layer, was not restored until after 3-4 months postcrush. The normal intense reactivity of the large-diameter optic axons and terminals at the bottom of the SFGS required an even longer period, about 7-8 months, for full recovery. The delayed restoration of C.O. reactivity was not due to a delay in synaptogenesis or in mitochondrial accumulation within optic terminals but to a delay in the maturation of mitochondrial reactivity. Following regeneration, the normal sublaminar stratification of C.O. bands was reestablished, suggesting that metabolically distinct classes of optic fibers may reinnervate at their original sublaminae. By using a distinct and persistent C.O. reactive sublamina, a of stratum griseum centrale (SGCa), just subjacent to the SFGS, it was possible to measure the thickness of the SFGS following optic denervation and subsequent reinnervation. At 1 week after optic nerve crush, the SFGS shrank by 35%. During regeneration, the thickness of the SFGS gradually increased to about 23% above normal at 2 months postcrush and this was maintained indefinitely. In the retina, ganglion cells were hypertrophic by 1 month postcrush and exhibited elevated levels of C.O. during the same period of time when optic terminals were unreactive. This indicates that oxidative metabolic activity within perikarya and axon terminals of the same neuron may be locally and independently regulated. It also suggests that in spite of the well-known elevation of axonal transport during the initial period of axon elongation and synaptogenesis, that oxidative metabolic energy production within the optic fibers is less than that of the mature projection.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1982

Muscle fibre differentiation and vascularisation in the juvenile European eel (Anguilla anguilla L.).

The differentiation of the lateral musculature in the elver stage of the European eel (Anguilla anguilla, L.) has been studied using histochemical staining techniques. Extracellular lipid deposits constitute 12% of the body cross-sectional area. Two fibre type may be distinguished on the basis of myofibrillar ATPase activity. Fibres with an alkaline-labile (pH 10.2) ATPase occur as a two-fibre layer around the trunk circumference, with invaginations along the horizontal septum and fin insertions. These pale-yellow fibres correspond to the slow ("red") fibres of other fish and comprise around 7% of the body cross-section (mean size, 167 micrometer2). Slow fibres show a moderate staining for PAS (glycogen), but a relatively weak reaction of Sudan black (lipid) and the aerobic enzyme markers succinic dehydrogenase (SDH) and cytochrome oxidase (COX). The bulk of the trunk muscle is composed of fast fibres (68%; 328 micrometer2). These are characterised by an alkaline (pH 10.2)-stable ATPase activity, and their innervation. Each fibre is innervated by a single "en-plaque" type endplate at one myoseptal end. Fast fibres adjacent to the slow fibre layer (2-4 fibres deep) show a moderate staining for PAS and a weak reaction for SDH and COX. Deeper regions show a wide range of fibre size, with about 5% being greater than 1,400 micrometer2. Fibres greater than 200 micrometer2 show no significant staining for glycogen, lipid, SDH, or COX. Small fast fibres less than 120 micrometer2 (up to 5% of the white muscle mass) show a strong staining reaction for PAS and a slight reaction for SDH and COX activities. Parameters of vascularisation were calculated from low-magnification electron micrographs (x 1,900). The number of capillaries/fibre and % fibre perimeter in contact with capillaries were, respectively, 0.98, 6.33% (slow fibres); 0.33, 1.96% (superficial fast fibres); and 0.12, 0.71% (deep fast fibres). These values are low in comparison with other fish species. It is suggested that the low aerobic capacity of elver slow muscle reflects a relatively restricted aerobic scope for activity associated with the anguilliform mode of locomotion.

Acetylcholinesterase↗
PubMed1988

Oxidative capacity of tissues contributing to thermogenesis in eider (Somateria mollissima) ducklings: changes associated with hatching.

1. The development of liver and skeletal muscle oxidative capacities during hatching of the common eider (Somateria mollissima) in the Arctic has been investigated by monitoring tissue cytochrome c oxidase activity. 2. The specific activity of the liver enzyme did not change as the embryo underwent hatching, nor during subsequent growth of the duckling into adulthood. 3. Thigh muscle enzyme specific activity increased by a factor of 3.4 during the 24 h prehatching period, remained elevated for at least 48 h after hatching, and then returned to the embryonic (-24 h) level in adults. 4. Histochemically visualized NADH-tetrazolium reductase of a typical red thigh muscle, M. vastus lateralis, showed a distinct increase in activity as the hatching process progressed to completion. 5. Electron microscopy of sectioned M. vastus lateralis revealed a dramatic increase in the density of the myofibrillar structure (number of mitochondrial profiles per unit area), and in the surface area of mitochondrial crista membranes in the course of the 48 h interval from 1 day prehatching to 1 day after hatching. 6. The significance of these changes for the scaling of thermoregulatory heat generation in the newly hatched eider duckling is discussed.

Animals↗
PubMed1976

Ca++-induced fusion of proteoliposomes: dependence on transmembrane osmotic gradient.

The fusion of cytochrome oxidase liposomes with liposomes reconstituted with mitochondrial hydrophobic protein is dependent on the presence of an acidic phospholipid in the liposomes and on the addition of Ca++ions. Liposomes which have grown, by fusion, to diameters in excess of 1000 A lose the ability to fuse further, unless an osmotic gradient across the liposome membrane is established, with the internal osmotic pressure higher than the external. At a given Ca++ concentration, the extent to which this second fusion step takes place is determined by the ratio of internal to external osmolarity. Single-walled liposomes with diameters exceeding 1 mumM have been produced by this technique. The data suggest that the thermodynamic driving force for the Ca++-induced fusion is an excess surface free energy which can be supplied by membrane curvature or transmembrane osmotic gradients.

Calcium↗
PubMed1999

Permeability of rat heart myocytes to cytochrome c.

Rat heart myocytes undergoing progressive damage demonstrate morphological changes of shortening and swelling followed by the formation of intracellular vacuoles and plasma membrane blebbing. The damaged myocytes displayed impaired N,N'-tetramethyl-p-phenyldiamine (TMPD) ascorbate-stimulated respiratory activity which was restored by the addition of reduced cytochrome c to the cell culture medium. To clarify the role played by cytochrome c in the impairment of cell respiration, polarographic, spectrophotometric and fluorescence as well as electron microscopy imaging experiments were performed. TMPD/ascorbate-stimulated respiratory activity returned to control levels, at approximately 20 microM cytochrome c, establishing the threshold below which the turnover rate by cytochrome c oxidase in the cell depends on cytochrome concentration. Mildly damaged cardiac myocytes, as indicated by cell shortening, retention of visible striations and free-fluorescein exclusion, together with the absence of lactate dehydrogenase leakage and exclusion of trypan blue, were able to oxidize exogenous cytochrome c and were permeable to fluorescein-conjugated cytochrome c. The results, while consistent with an early cytochrome c release observed at the beginning of cell death, elucidate the role played by cytochrome c in the kinetic control of mitochondrial electron transfer under pathological conditions, particularly those involving the terminal part of the respiratory chain. These data are the first to demonstrate that the sarcolemma of cardiac myocytes, damaged but still viable, is permeable to cytochrome c.

Animals↗
PubMed1987

Mitochondrial myopathy involving ubiquinol-cytochrome c oxidoreductase (complex III) identified by immunoelectron microscopy.

The distribution of respiratory chain complexes in bovine heart and human muscle mitochondria has been explored by immunoelectron microscopy with antibodies made against bovine heart mitochondrial proteins in conjunction with protein A-colloidal gold (12-nm particles). The antibodies used were made against NADH-coenzyme Q reductase (complex I), ubiquinol cytochrome c oxidoreductase (complex III), cytochrome c oxidase, core proteins isolated from complex III and the non-heme iron protein of complex III. Labeling of bovine heart tissue with any of these antibodies gave gold particles randomly distributed along the mitochondrial inner membrane. The labeling of muscle tissue from a patient with a mitochondrial myopathy localized by biochemical analysis to complex III was quantitated and compared with the labeling of human control muscle tissue. Complex I and cytochrome c oxidase antibodies reacted to the same level in myopathic and normal muscle samples. Antibodies to complex III or its components reacted very poorly to the patient's tissue but strongly to control muscle samples. Immunoelectron microscopy using respiratory chain antibodies appears to be a promising approach to the diagnosis and characterization of mitochondrial myopathies when only limited amounts of tissue are available for study.

Electron Transport↗