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Biomedical subjects

B R Pachter

Publications and source records attributed to B R Pachter.

At least 37 records · Page 2Linked to original sources
PubMed1986

Motor endplate involvement in the extraocular muscles of the myotonic rat.

The motor endplates from the extraocular muscles of rats administered 20,25-diazacholesterol were examined by electron microscopy. Many anomalies were found at various levels of the junctional complex. Electron microscopy showed disrupted sole-plate nuclei, disruptions of the junctional sarcoplasm, atypical sarcoplasmic extensions, simplified postsynaptic areas, and interposition of Schwann cell cytoplasm between axonal terminal and muscle fiber with a reduplication of basement membrane, as well as atrophic and disrupted axonal terminals. These data indicate that the motor endplate is affected as well as the muscle fiber in myotonic dystrophy.

Animals↗
PubMed1984

Neuromuscular plasticity following limb immobilization.

The effects of immobilization on the ultrastructure of the rat neuromuscular junction of type I and type II muscle fibres were studied both qualitatively and quantitatively. Muscle fibre areas were measured as well. The plantaris muscle was immobilized in a shortened position by applying a plaster cast for three weeks. Immobilized muscles were then compared to normal litter mates. Both type I and type II immobilized muscle fibres atrophied. Endplates from type II muscle fibres exhibited greater amounts of degeneration than type I endplates. Degeneration consisted of nerve terminal disruption, exposed junctional folds, postsynaptic areas which contained little or no postjunctional folds, and subjunctional sarcoplasmic masses. In addition to degeneration, the type II endplates also exhibited regeneration in the same endplate consisting of small terminals associated with large expanses of junctional folds, several small terminals occurring within the same primary synaptic cleft, and several axons wrapped by the same Schwann cell. These observations suggest terminal axonal regeneration. Our results demonstrate that limb immobilization produces muscle atrophy as well as denervation-like changes at the neuromuscular junctions which leads to terminal axonal sprouting and an ultrastructural remodelling.

Animals↗
PubMed1984

Rat extraocular muscle. 3. Histochemical variability along the length of multiply-innervated fibers of the orbital surface layer.

Multiply-innervated fibers from rat superior oblique extraocular muscle were followed in sequential serial sections using histochemistry. Sudan black and adenosine-triphosphatase (ATPase) histochemical staining reactions were used to identify these fibers in the muscle's global layer and orbital surface layer. Regional differences in ATPase staining occurred along the length of multiply-innervated fibers from the orbital surface layer. In their middle third where these fibers appear 'morphologically-fast' and contain endplatelike endings, they were found to exhibit a dual ATPase activity. In their distal third where they appear 'morphologically-slow' and contain simple, superficial endings, they had an alkaline-labile and acid-stabile ATPase activity profile. In contrast, the multiply-innervated fibers of the global layer exhibited a homogeneous ATPase activity, i.e., alkaline-labile and acid-stabile pattern. This histochemical homogeneity parallels their uniform morphologically-slow profile. These fibers contain only multiple superficial endings. It would appear that the histochemical and ultrastructural profile of a fiber is dependent upon the type and location of the motor innervation.

Adenosine Triphosphatases↗
PubMed1983

Endplate postsynaptic structure dependent upon muscle activity.

The influence of contractile activity on the preservation of the denervated postsynaptic region of the endplate was quantitatively assessed by electron microscopy. The extensor digitorum longus muscle of rats were denervated for 21 days. Denervated animals were divided into two groups, those receiving electrical stimulation treatment (1 h/day for 21 days) and those left untreated. The postsynaptic area of clefts and folds in endplates of type I and II muscle fibers from controls and denervated-stimulated animals were found to be comparable in size whereas the postsynaptic areas in the denervated-non-stimulated muscles were significantly reduced. The results show that electrically-induced contractile activity plays a significant role in the maintenance of the postsynaptic region of the endplate.

Animals↗
PubMed1983

Rat extraocular muscle. 2. Histochemical fibre types.

A battery of histochemical stains was used to differentiate the component fibre populations in rat superior oblique muscle. Seven histochemical fibre types were identified and found to be comparable to those observed in a prior light and electron microscopic study of the muscle. The global region of the muscle contained three singly innervated fibre populations (pale, intermediate and red) and one of multiply innervated fibres. THe global singly innervated fibre populations produced a spectrum of fibre types with trichrome, succinate dehydrogenase and Sudan black. The overlying orbital surface layer contained two populations of singly innervated fibres and an additional population of multiply innervated fibres. All the singly innervated fibres (both global and orbital) exhibited a high mATPase activity at pH 10.4 and a low mATPase activity at pH 4.6. The global multiply innervated fibres had low mATPase activity at pH 10.4 and high mATPase activity at pH 4.6. The multiply innervated fibres of the orbital surface layer exhibited high mATPase activity at pH 10.4 and at pH 4.6. The global multiply innervated fibres are similar to the tonic fibres found in amphibian muscle, both histochemically and ultrastructurally. Based upon their histochemical reactivities with the various stains, the multiply innervated fibres of the orbital surface layer appear to be faster acting than the global multiply innervated fibres. Furthermore, it is postulated that the former have polyneuronal innervation and are capable of dual mATPase synthesis.

Adenosine Triphosphatases↗
PubMed1983

Rat extraocular muscle. 1. Three dimensional cytoarchitecture, component fibre populations and innervation.

Rat superior oblique extraocular muscle was examined in serial sections by light and electron microscopy. By such analysis, it was possible to discriminate single versus multiply innervated fibres, characteristics of the internal structure of fibres, and topographical distribution of the respective fibre populations within the muscle. The superior oblique muscle was observed to consist of two distinguishable muscle portions; one portion originated proximally and the other muscle portion originated distally after passing through the trochlea tendon. Seven morphologically distinct fibre populations were discernible. Four populations, three singly innervated fibre populations and one multiply innervated fibre population, were localised in the global region; these differed in terms of diameter, mitochondrial richness, development of the sarcoplasmic reticulum and myofibrillar size. The orbital surface layer contained two singly innervated and one multiply innervated populations; all of these exhibited systematic morphological variability. The multiply innervated fibres displayed multiple, relatively superficial, neuromuscular junctions along their length, as well as end plate-like junctions which were apparently confined to the region of the singly innervated fibre innervation band, thus suggesting polyneuronal innervation. In the latter region, the multiply innervated fibres displayed morphological features characteristic of "twitch' fibres; away from this region these cells appeared to have morphological features typical of "tonic' fibres. In contrast, the global multiply innervated fibres were constant diameter and form along their length, and displayed only relatively superficial neuromuscular junctions.

Animals↗
PubMed1982

Fiber composition of the superior rectus extraocular muscle of the rhesus macaque.

The fiber composition of the superior rectus extraocular muscle of adult rhesus monkeys (Macaca mulatta) was examined in serial sections by light and electron microscopy as well as morphometry. Analyses allowed separation of singly versus multiply innervated fibers, and disclosed the morphology of these fibers and their topographical distribution within the muscle. Six morphologically distinct fiber types were found. The global layer of the muscle contains three singly innervated fibers (SIFs) and one multiply innervated fiber (MIF). The overlying orbital surface layer contains one SIF and one MIF, both showing morphological variation along their length. The MIFs of the orbital surface layer had not only multiple, relatively superficial endings along their length, but also endplatelike junctions in which the axonal terminals lie within synaptic clefts. These endplatelike junctions were confined to that region of the MIFs that had a morphology typical of "twitch" fibers; away from this region these MIFs had a morphology characteristic of "tonic" fibers. In contrast, the global MIFs showed constant morphology, and did not exhibit endplatelike endings.

Animals↗
PubMed1982

Electrical stimulation effect on denervated skeletal myofibers in rats: a light and electron microscopic study.

The purpose of the present study was to determine morphologically the effect of electrical stimulation on denervated rat extensor digitorum longus (EDL) muscle. Fifteen adult male rats were divided in to 3 groups: control, denervated-nonstimulated, and denervated-stimulated. Electrical stimulation treatment (1 hr/day for 24 days) began 4 days postsurgery. All animals were sacrificed 28 days after surgery; the EDL muscle was fixed in situ, removed, and processed for light and electron microscopic examination. Fibers from sections taken from the middle third of the muscle were differentiated into types I and II; fiber diameters were obtained and compared for each experimental group. Although both types atrophied following denervation, type I atrophied to a lesser extent than type II. Electrical stimulation was beneficial in retarding denervation atrophy for both types. Membrane-glycogen complexes were found on electron microscopy to be in high proportion in type II stimulated fibers but were observed infrequently in denervated nonstimulated muscles and were not apparent in control muscles. These glycogen arrays may be expressions of sarcoplasmic reticulum anabolic functions, indicating a high degree of regenerative metabolic activity in treated fibers. This study indicates that electrical stimulation as a method to induce muscle activity, can retard denervation atrophy.

Animals↗
PubMed1977

Structural alterations of extraocular muscle associated with Apert's syndrome.

An inferior oblique muscle from a patient with Apert's syndrome was examined by light and electron microscopy. Alterations in the muscle fibres, the myoneural junctions, and intramuscular nerves were observed. These data are not compatible with the widespread notion that motility disturbances in this syndrome are solely due to mechanical limitations.

Acrocephalosyndactylia↗
PubMed1977

Double-membrane arrays in type II fibers of mouse extraocular muscle.

Double-membrane arrays were observed in singly innervated type II fibers of the global region of mouse superior rectus. These arrays were selectively confined to the endplate region of such cells. Close associations and continuities between the cisternae of the arrays with those of the intermyofibrillar sarcoplasmic reticulum suggest derivation of the former from the latter. These proliferations of the cellular smooth membranes might be related to the specialized functional requirements of the innervation site.

Animals↗
PubMed1976

Light and electron microscopic serial analysis of mouse extraocular muscle: morphology, innervation and topographical organization of component fiber populations.

Mouse superior rectus extraocular muscle was examined in serial section by light and electron microscopy. By such analysis, it was possible to discriminate single versus multiple innervation, characteristics of internal cell morphology, and topographical distribution of the respective fiber populations within the muscle. Singly innervated (SIF) and multiply innervated fibers (MIF) were observed, both in an orbital surface layer and in the underlying global region of the muscle. Five morphologically distinct fiber types (three SIF and two MIF) were discriminable in terms of fiber diameter, mitochondrial richness, development of the sarcoplasmic reticulum, and myofibrillar size. Many fibers both SIF and MIF, terminated variously along the length of the muscle. The diameter of orbital MIF typically varied from one end of the fiber to the other by a factor of about three; the global MIF were of essentially constant diameter. The junctional complexity varied among the respective types of SIF. The MIF of both the global and orbital regions exhibited comparable ranges of complexity in their neuromuscular junctions.

Animals↗
PubMed1976

Congenital total external ophthalmoplegia associated with infantile spinal muscular atrophy. Fine structure of extraocular muscle.

A case of total congenital external ophthalmoplegia associated with infantile spinal muscular atrophy is presented. In the first 29 months of life, ophthalmoplegia has remained complete. Ultrastructure of lateral rectus extraocular muscle indicates a neurogenic process as the basis of the ophthalmoplegia. Light microscopy alone is insufficient to distinguish primary "myopathic" from "neurogenic" disease in external eye muscles.

Child, Preschool↗