Histochemistry of some trout respiratory muscles.

A histochemical study has been made of the main cranial muscles which produce ventilation movements of the rainbow trout. It is shown that a greater proportion of red(aerobic) fibres is present in those muscles known to be active during shallow ventilation than those which become active at greater ventilation volumes. An ordered recruitment of red, pink and white fibres within these muscles is also likely.     

Histochemistry of some trout respiratory muscles

Summary A histochemical study has been made of the main cranial muscles which produce ventilation movements of the rainbow trout. It is shown that a greater proportion of red(aerobic) fibres is present in those muscles known to be active during shallow ventilation than those which become active at greater ventilation volumes. An ordered recruitment of red, pink and white fibres within these muscles is also likely.This work was carried out when I.A. Johnston was holding an NERC Post-Doctoral Research Fellowship (1973–75).     

Enzymatic activities of muscle fibres differentiated,in vitro,from pectoralis major (white) and adductor magnus (red) muscles of chick embryos

Summary Specific activities of NADP isocitrate dehydrogenase and acetylcholinesterase were significantly higher in muscle fibres differentiated, in vitro, from myoblasts of adductor magnus (red) than pectoralis major (white) muscles 10-day-old chick embryos. This is evidence, as far as enzyme activities, are concerned, that myoblasts from different types of skeletal muscles are able to give, in tissue culture, muscle fibres of different properties, even in the absence of nerve supply.Supported by a grant No. 75 7 1641 from the French Délégation à la Recherche scientifique et technique.     

Elektronenmikroskopische Untersuchungen an Zellulosefasern nach Behandlung mit Ultraschall

Summary Treating natural cellulose fibres with ultrasonic waves, fine fibrils split off, which easily can be studied with the electronmicroscope. Bundles of cellulose-molecules with various diameters, very frequently 60–70 Å wide, are found. Their length seems not to be limited within the fibres.     

Ultrastructure of muscle spindles in C57BL/6J dy2J/dy2J dystrophic mice.

The sensory organs of skeletal muscles, the muscle spindles, were examined using electron microscopy in dy2J/dy2J dystrophic mice. Despite widespread damage to the extrafusal (skeletomotor) fibres the intrafusal (spindle) fibres appeared normal and seemed resistant to the aetiological factors for murine dystrophy.     

Ultrastructural differences in mitochondria of skeletal muscle in the prerigor and rigor states.

Loss of cristae and matrix occur in the mitochondria of skeletal muscles prior to any observable changes in myofibrillar proteins during the development of rigor mortis. Care must be observed because ultrastructural changes in mitochondria in some studies may be attributed to a specific trauma, whereas the changes may be due to the lower pH in postmortem muscle.     

Spirally arranged muscles associated with tracheoles in tsetse fly flight muscles; their possible involvement in sound production

Summary A set of muscle fibres have been found associated with certain tracheoles in the flight muscles of the tsetse fly. It is proposed that those muscles may be involved in sound production in the fly.I am grateful to the Ministry of Overseas Development for a grant in support of this work and to Professor L.H. Finlayson for his advice and criticism.     

Thick filament size changes in contraction of human muscles

Summary Measurements done on electron micrographs show that in myofibres with sarcomeres contracted to below 2.1 m, proportional shortening of the A bands occurs. In muscles from patients with idiopathic scoliosis very short A bands are especially prominent.This work was supported by the Muscular Dystrophy Association of America.We wish to thank H. Orgal and Y. Havivi, for their technical assistance, O. Carmi and B. Ghidoni for their help with the measurements and N. Vagenberg for the computer analyses.     

Ultrastructural differences in mitochondria of skeletal muscle in the prerigor and rigor states

Summary Loss of cristae and matrix occur in the mitochondria of skeletal muscles prior to any observable changes in myofibrillar proteins during the development of rigor mortis. Care must be observed because ultrastructural changes in mitochondria in some studies may be attributed to a specific trauma, whereas the changes may be due to the lower pH in postmortem muscle.Scientific Journal Series, Paper No. 9633, Minnesota Agricultural Experiment Station.     

Differentiating abilities of avian somatopleural mesoderm.

Quail-to-chick grafting experiments were performed on 2-day embryos in order to test the differentiating abilities of the somatopleure. After orthotopic and heterotopic transplatations of different parts of quail somatopleural mesoderm into chick embryos it is demonstrated that avian somatopleural cells differentiate into skeletal elements, smooth muscles, tendons and connective tissues. However, skeletal muscle fibres do not originate from somatopleural cells.     

Hypoxia increases potassium efflux from mammalian myocardium.

Hypoxia with or without simultaneous depletion of extracellular glucose increases 42K-efflux in cat and guinea-pig papillary muscles and bovine Purkinje fibres. The change observed in K efflux may be the result of an increase in K conductance at rest.     

New observations on the representation of the eye muscle proprioception within the descending trigeminal nucleus.

Units responding to stretch of single extraocular muscles were found in the bulbar and cervical portion of the descending trigeminal nucleus of the lamb. The electrolysis of these bulbar sites provoked degeneration of nervous fibres which could be followed till the first cervical segment of the spinal cord.     

Ultrastructure of muscle spindles in C57BL/6Jdy 2J/dy 2J dystrophic mice

Summary The sensory organs of skeletal muscles, the muscle spindles, were examined using electron microscopy indy ^2J/dy ^2J dystrophic mice. Despite widespread damage to the extrafusal (skeletomotor) fibres the intrafusal (spindle) fibres appeared normal and seemed resistant to the aetiological factors for murine dystrophy.This work was supported by grants from the Medical Research Council and the Science Research Council of Great Britain.     

Effects of inhibition and stimulation of Na+-K+ active transport on the resting membrane input conductance of the guinea-pig ventricle

The effects of inhibition by ouabain and stimulation by high frequency drive of the sarcolemmal Na+-K+ active transport system on the resting input conductance (gi) of guinea-pig ventricular muscles were determined. Although both pump inhibition and stimulation were associated with changes in electrophysiological properties of the muscles, neither had a significant effect on gi.     

Differentiating abilities of avian somatopleural mesoderm

Summary Quail-to-chick grafting experiments were performed on 2-day embryos in order to test the differentiating abilities of the somatopleure. After orthotopic and heterotopic transplantations of different parts of quail somatopleural mesoderm into chick embryos it is demonstrated that avian somatopleural cells differentiate into skeletal elements, smooth muscles, tendons and connective tissues. However, skeletal muscle fibres do not originate from somatopleural cells.Supported by a grant from the Deutsche Forschungsgemeinschaft (Ch 44/3).     

On the heterogeneity of skeletal muscle fibers: The intermediate fibers

Résumé Les mesures d'intensité de la réaction à la succino-déshydrogénase et de la surface des fibres des muscles quadriceps et soléaire chez le rat nous ont permis d'individualiser un groupe de fibres intermédiaires qui se situe entre les fibres rouges (type I) et blanches (type II). Les fibres intermédiaires ont une activité enzymatique et une population mitochondriale distinctes, une taille moyenne et une teneur élevée en glycogène.     

Hypoxia increases potassium efflux from mammalian myocardium

Summary Hypoxia with or without simultaneous depletion of extracellular glucose increases⁴²K-efflux in cat and guinea-pig papillary muscles and bovine Purkinje fibres. The change observed in K efflux may be the result of an increase in K conductance at rest.Aspirant-navorser van het Nationaal Fonds voor Wetenschappelijk Onderzoek.     

Frequencygrams due to the stimulation of dynamic gamma axons exerting type II effects]

Frequencygrams are graphs giving indirect information on the contraction of intrafusal muscle fibres. Frequencygrams of Cat spindle primary endings (flexor hallucis longus, soleus and peroneus brevis muscles) were recorded during repetitive stimulation of dynamic gamma axons exerting type II effects. The features of these frequencygrams (periodic increments whose frequency is equal to that of the stimulation and "driving") show that they can be ascribed to a relatively strong and fast intrafusal contraction. Two interpretations are considered.     

A morphological study of delayed muscle soreness

Summary Biopsies, taken up to 1 week postexercise, from the soleus muscles of 5 healthy males (20–34 years old) suffering from pronounced exercise-induced delayed muscle soreness were analyzed morphologically. There was no evidence for ischemic tissue injury or mechanical fibre disruption. However, at the subcellular level frequent myofibrillar disturbances, especially with regard to the Z-bands, were noted. Thus, the contractile machinery of overloaded muscle fibres seemed to be partially distorted several days following exercise.     

Variation in the number and size of myelinated nerve fibers regenerated after repeated localized freezing of the sciatic nerve of rats]

The number and size of myelinated fibres have been determined in the nerve to medial head of the gastrocnemius muscle of Rats in which the sciatic nerve had been frozen locally 1 to 5 times at monthly intervals. The contralateral nerve was used as a control. When the measurements were made one month after the last freezing, the number of fibres increased progressively until the 3rd freezing, reaching about 220% of the normal value. No higher values were observed after 4 or 5 freezings. The mean diameter of fibres decreased with the number of operations. When the measurements were made 3, 6, 12 or 18 months after the 3rd freezing, the number of fibres decreased by about 30% between the 1st and the 3rd month and then stabilized. The mean diameter of fibres increased progressively. However, at the 18th month, the size of the myelinated fibres had not reached the normal value.