scholarly journals Morphological peculiarities of neuromuscular junctions among different fiber types: Effect of exercise

2017 ◽  
Vol 27 (3) ◽  
Author(s):  
Teet Seene ◽  
Maria Umnova ◽  
Priit Kaasik
Keyword(s):  
Axon Terminal ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Fiber Types ◽  
Sectional Area ◽  
Cross Sectional ◽  
Thin Sections ◽  
Axon Terminals ◽  
Ultrastructural Studies

The aim of our research was to examine whether there are differences in the morphology of neuromuscular junctions of different types of muscle fibers in rodents, and after their adaptation to six weeks endurance exercise training. After 5-day acclimation, Wistar rats were subjected to run with the speed 35 m/min during 6 week, 5 days per week and the training volume reached 60 min per day. Muscle samples for ultrastructural studies were fixed, dehydrated and embedded in Epon-812. Ultra-thin sections were cut from longitudinally and transversely oriented blocs, using 4 blocks from each animal. The area of axon terminals on fast- twitch fibers is 1.5 time large (p<0.001) and the perimeter of terminals is 1.7 time large in comparison with slow- twitch oxidative fibers (p<0.001) in control group. There are correlation between cross-sectional area of different muscle fibers and length of axon terminals (r=0.72), between cross-sectional area and with of axon terminal (r=-0.62), and between turnover rate of contractile proteins and length of axon terminal (r=0.75). Fast remodeling of synapse on oxidative and oxidative-glycolytic muscle fibers during endurance training seems to guarantees the intensive renewal of the structures of muscle fibers with higher oxidative capacity.

Absence of regional differences in the size and oxidative capacity of diaphragm muscle fibers

1987 ◽  
Vol 63 (3) ◽  
pp. 1076-1082 ◽  
Author(s):  
G. C. Sieck ◽  
R. D. Sacks ◽  
C. E. Blanco
Keyword(s):  
Muscle Fibers ◽  
Continuous Distribution ◽  
Oxidative Capacity ◽  
Cross Sectional Area ◽  
Diaphragm Muscle ◽  
Type I ◽  
Fiber Types ◽  
Sectional Area ◽  
Cross Sectional ◽  
Fast Twitch

The oxidative capacity and cross-sectional area of muscle fibers were compared between the costal and crural regions of the cat diaphragm and across the abdominal-thoracic extent of the muscle. Succinate dehydrogenase (SDH) activity of individual fibers was quantified using a microphotometric procedure implemented on an image-processing system. In both costal and crural regions, population distributions of SDH activities were unimodal for both type I and II fibers. The continuous distribution of SDH activities for type II fibers indicated that no clear threshold exists for the subclassification of fibers based on differences in oxidative capacity (e.g., the classification of fast-twitch glycolytic and fast-twitch oxidative glycolytic fiber types). No differences in either SDH activity or cross-sectional area were noted between fiber populations of the costal and crural regions. Differences in SDH activity and cross-sectional area were noted, however, between fiber populations located on the abdominal and thoracic sides of the costal region. Both type I and II fibers on the abdominal side of the costal diaphragm were larger and more oxidative than comparable fibers on the thoracic side.

Muscle fiber architecture of the dog diaphragm

1998 ◽  
Vol 84 (1) ◽  
pp. 318-326 ◽  
Author(s):  
Aladin M. Boriek ◽  
Charles C. Miller ◽  
Joseph R. Rodarte
Keyword(s):  
Connective Tissue ◽  
Muscle Fiber ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Fiber Architecture ◽  
Cross Sectional ◽  
Diaphragmatic Muscle ◽  
Muscle Fiber Architecture

Boriek, Aladin M., Charles C. Miller III, and Joseph R. Rodarte. Muscle fiber architecture of the dog diaphragm. J. Appl. Physiol. 84(1): 318–326, 1998.—Previous measurements of muscle thickness and length ratio of costal diaphragm insertions in the dog (A. M. Boriek and J. R. Rodarte. J. Appl. Physiol. 77: 2065–2070, 1994) suggested, but did not prove, discontinuous muscle fiber architecture. We examined diaphragmatic muscle fiber architecture using morphological and histochemical methods. In 15 mongrel dogs, transverse sections along the length of the muscle fibers were analyzed morphometrically at ×20, by using the BioQuant System IV software. We measured fiber diameters, cross-sectional fiber shapes, and cross-sectional area distributions of fibers. We also determined numbers of muscle fibers per cross-sectional area and ratio of connective tissue to muscle fibers along a course of the muscle from near the chest wall (CW) to near the central tendon (CT) for midcostal left and right hemidiaphragms, as well as ventral, middle, and dorsal regions of the left costal hemidiaphragm. In six other mongrel dogs, the macroscopic distribution of neuromuscular junctions (NMJ) on thoracic and abdominal diaphragm surfaces was determined by staining the intact diaphragmatic muscle for acetylcholinesterase activity. The average major diameter of muscle fibers was significantly smaller, and the number of fibers was significantly larger midspan between CT and CW than near the insertions. The ratio of connective tissues to muscle fibers was largest at CW compared with other regions along the length of the muscle. The diaphragm is transversely crossed by multiple scattered NMJ bands with fairly regular intervals offset in adjacent strips. Muscle fascicles traverse two to five NMJ, consistent with fibers that do not span the entire fascicle from CT to CW. These results suggest that the diaphragm has a discontinuous fiber architecture in which contractile forces may be transmitted among the muscle fibers through the connective tissue adjacent to the fibers.

Regulation of fiber size, oxidative potential, and capillarization in human muscle by resistance exercise

1999 ◽  
Vol 276 (2) ◽  
pp. R591-R596 ◽  
Author(s):  
H. Green ◽  
C. Goreham ◽  
J. Ouyang ◽  
M. Ball-Burnett ◽  
D. Ranney
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Succinic Dehydrogenase ◽  
Quadriceps Muscle ◽  
Cellular Tissue ◽  
Cross Sectional Area ◽  
Fiber Types ◽  
Sectional Area ◽  
Oxidative Potential ◽  
Cross Sectional

To examine the hypothesis that increases in fiber cross-sectional area mediated by high-resistance training (HRT) would result in a decrease in fiber capillarization and oxidative potential, regardless of fiber type, we studied six untrained males (maximum oxygen consumption, 45.6 ± 2.3 ml ⋅ kg−1 ⋅ min−1; mean ± SE) participating in a 12-wk program designed to produce a progressive hypertrophy of the quadriceps muscle. The training sessions, which were conducted 3 times/wk, consisted of three sets of three exercises, each performed for 6–8 repetitions maximum (RM). Measurements of fiber-type distribution obtained from tissue extracted from the vastus lateralis at 0, 4, 7, and 12 wk indicated reductions ( P < 0.05) in type IIB fibers (15.1 ± 2.1% vs. 7.2 ± 1.3%) by 4 wk in the absence of changes in the other fiber types (types I, IIA, and IIAB). Training culminated in a 17% increase ( P < 0.05) in cross-sectional area by 12 wk with initial increases observed at 4 wk. The increase was independent of fiber type-specific changes. The number of capillaries in contact with each fiber type increased by 12 wk, whereas capillary contacts-to-fiber area ratios remained unchanged. In a defined cross-sectional field, HRT also increased the capillaries per fiber at 12 wk. Training failed to alter cellular oxidative potential, as measured by succinic dehydrogenase (SDH) activity, regardless of fiber type and training duration. It is concluded that modest hypertrophy induced by HRT does not compromise cellular tissue capillarization and oxidative potential regardless of fiber type.

Maximal force as a function of anatomical features of motor units in the cat tibialis anterior

1987 ◽  
Vol 57 (6) ◽  
pp. 1730-1745 ◽  
Author(s):  
S. C. Bodine ◽  
R. R. Roy ◽  
E. Eldred ◽  
V. R. Edgerton
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Periodic Acid ◽  
Muscle Fibers ◽  
Motor Units ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Periodic Acid Schiff ◽  
Cross Sectional ◽  
Single Motor Unit

In 11 tibialis anterior muscles of the cat, a single motor unit was characterized physiologically and subsequently depleted of its glycogen through repetitive stimulation of an isolated ventral root filament. Muscle cross sections were stained for glycogen using a periodic acid-Schiff reaction, and single-fiber optical densities were determined to identify those fibers belonging to the stimulated motor unit. Innervation ratios were determined by counting the total number of muscle fibers in a motor unit in sections taken through several levels of the muscle. The average innervation ratios for the fast, fatigueable (FF) and fast, fatigue-resistant (FR) units were similar. However, the slow units (S) contained 61% fewer fibers than the fast units (FF and FR). Muscle fibers belonging to S and FR units were similar in cross-sectional area, whereas fibers belonging to FF units were significantly larger than fibers belonging to either S or FR units. Additionally, muscle fibers innervated by a single motoneuron varied by two- to eightfold in cross-sectional area. Specific tensions, based on total cross-sectional area determined by summing the areas of all muscle fibers of each unit, showed a modest difference between fast and slow units, the means being 23.5 and 17.2 N X cm-2, respectively. Variations in maximum tension among units could be explained principally by innervation ratio, although fiber cross-sectional area and specific tension did contribute to differences between unit types.

scholarly journals Comparison of M.Semitendinosus Morphometry and Structure in Gilts and Barrows at Market Age

2016 ◽  
Vol 66 (1) ◽  
pp. 132-137
Author(s):  
Ivana Božičković ◽  
Duško Vitorović ◽  
Miloš Blagojević ◽  
Ivana Nešić ◽  
Slavoljub Jović ◽  
...  
Keyword(s):  
Cross Sectional Area ◽  
Histological Structure ◽  
Fiber Types ◽  
Sectional Area ◽  
Morphometric Characteristics ◽  
Cross Sectional ◽  
Fiber Number ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Very High

AbstractThe aim of this paper was to investigate the differences in morphometric characteristics and histological structure of m. semitendinosus, between gilts and barrows of German Landrace breed at the end of the fattening period. Morphometric characteristics (weight, length, diameter and cross sectional area) of m. semitendinosus were not significantly different, while gender as a factor influenced the histological properties of this muscle. A very high statistical difference (p<0.01) in the total number of muscle fibers in m. semitendinosus was determined, with gilts having a higher total fiber number. The cross sectional area of fast twitch oxidative (FTO) fibers was significantly higher (p<0.05) in barrows. Gender did not affect the distribution of different fiber types: in both gender, the most present fiber types (48-52 %) were fast twitch glycolitic (FTG), FTO fibers represented 27-30 % of the total fiber number, while slow twitch oxidative fibers (STO) were the least represented (≈ 20 %).

Morphometric Analysis of Platelets in Bernard-Soulier Syndrome: Size and Configuration in Patients and Carriers

1984 ◽  
Vol 52 (01) ◽  
pp. 037-041 ◽  
Author(s):  
M McGill ◽  
G A Jamieson ◽  
J Drouin ◽  
M S Cho ◽  
G A Rock
Keyword(s):  
Morphometric Analysis ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Thin Sections ◽  
Bernard Soulier Syndrome

SummaryQuantitative ultrastructural morphometric analysis has been carried out on thin sections of platelets from two Bernard-Soulier sisters and their parents. Measurements were made for the major and minor axes, axial ratios, cross-sectional circumference and cross-sectional area. Platelets were collected either into CPD anticoagulant or directly into glutaraldehyde. The results confirm that Bemard-Soulier platelets are significantly larger than normals (p <0.05) in all the parameters mentioned and indicate (I) that the morphology of platelets from Bernard-Soulier patients is affected by the presence of anticoagulant, and (II) a more spherocytic configuration is characteristic of Bemard-Soulier disease both in patients and carriers.

Morphological observations of motor units connected in-series to Golgi tendon organs

1986 ◽  
Vol 55 (1) ◽  
pp. 147-162 ◽  
Author(s):  
J. M. Spielmann ◽  
E. K. Stauffer
Keyword(s):  
Discharge Rate ◽  
Muscle Fibers ◽  
Motor Units ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Golgi Tendon Organs ◽  
In Series ◽  
The Cross ◽  
Tendon Organs

The glycogen-depletion technique (17, 32) has been used to examine the functional and morphological relationships between single isolated motor units (MUs) and single isolated Golgi tendon organs (GTOs) that were excited by the MUs in the soleus muscle of the cat. All MUs whose twitch contraction generated a brisk discharge from the GTOs during the rising and plateau phase of force development had a muscle fiber attached specifically to the proximal end of the GTOs. A significant (P less than 0.05) linear relationship was found between GTO discharge rate and the cross-sectional area of the muscle fibers that connected to a receptor. This was true when the correlation was calculated between firing rate and 1) the cross-sectional area of the entire collection of muscle fibers that connected in series to the GTOs; and 2) for the cross-sectional areas of the individually depleted muscle fibers that inserted on the GTO sample. These findings support the notion that the most physiologically relevant input for GTOs arises from the MUs that are attached directly in-series with the receptor.

Effects of starvation and refeeding on adult male rat diaphragm contractility, fatigue, and fiber types

1993 ◽  
Vol 74 (2) ◽  
pp. 742-749 ◽  
Author(s):  
D. J. Prezant ◽  
D. E. Valentine ◽  
H. H. Kim ◽  
E. I. Gentry
Keyword(s):  
Fatigue Resistance ◽  
Cross Sectional Area ◽  
Male Rats ◽  
Male Rat ◽  
Type I ◽  
Fiber Types ◽  
Type Ii ◽  
Sectional Area ◽  
Cross Sectional ◽  
Type Ii Fibers

The effects of 4.5 days of acute starvation, either alone or followed by refeeding (ad libitum), on diaphragm contractility, fatigue, and fiber types were studied in male rats. Contractility and fatigue resistance indexes were measured in an in vitro costal diaphragm strip preparation with direct stimulation at 37 degrees C. Compared with controls, starvation produced a 28 +/- 1% (P < 0.001) reduction in body weight and an 18 +/- 4% (P < 0.001) reduction in costal diaphragm weight. Twitch and tetanic tensions (normalized for weight or cross-sectional area) were not reduced by starvation. Starvation produced significant increases in fatigue resistance indexes after a 5-Hz stimulation paradigm but not after a 100-Hz paradigm, supporting the hypothesis that fatigue resistance is dependent on the energy demand of a given paradigm. The proportions of type I and type II fibers were similar between diaphragms of starved and control rats, but the cross-sectional area of type II fibers decreased significantly by 18 +/- 7% (P < 0.01). Thus, despite the significant decrease in diaphragm weight after starvation, contractility was preserved and fatigue resistance was increased (low-output paradigm). This is consistent with the decrease in type II fiber area. Refeeding restored all parameters so that there were no longer significant differences in body or diaphragm weight, contractility, fatigue, or fiber types.

Free autografting of entire limb muscles in the cat: histochemistry and biochemistry

1978 ◽  
Vol 44 (3) ◽  
pp. 431-437 ◽  
Author(s):  
L. C. Maxwell ◽  
J. A. Faulkner ◽  
S. A. Mufti ◽  
A. M. Turowski
Keyword(s):  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Succinate Dehydrogenase Activity ◽  
Cross Sectional ◽  
The Mean ◽  
Fast Twitch

Fifty extensor digitorium longus muscles of 25 cats were autografted, 33 with and 17 without prior denervation. After 50 days, no significant differences were observed between predenervated and nonpredenervated autografts. Autografted muscles weighed 48% of the weight of control muscles. Few original muscle fibers survived and within 2 wk autografts contained regenerating muscle fibers. The mean cross-sectional area of muscle fibers in the autografts reached 125% of the value for control nontransplanted muscles. The mean percentage of fibers classified high oxidative in autografted muscles was 67% of values for control muscles. SDH activity of autografted muscle homogenates reached 55% of control values. Up to 60 days after surgery autografts had only fast-twitch fibers. At 170 days autografts remained 95% fast twitch in composition. Revascularization began within 4 days, but the capillary to fiber ratio of long term autografts reached only 60% of control values. Although fiber hypertrophy suggests that cats use autografted muscles, lower than control succinate dehydrogenase activity may result from altered recruitment.

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