Differences In Fiber Size Research Articles

Relationships Between Retained Amphibole Fibres and Fibrosis in Human Lung Tissue Specimens

Tissue specimens were obtained from post-mortem lungs of workers who had been employed at one of four amphibole mining locations: Paakkila (Finland), anthophyllite; Wittenoom (Australia), crocidolite; North Western Cape Province (NW Cape; South Africa), crocidolite; Transvaal (South Africa), amosite and crocidolite. A method based on combined magnetic alignment and light scattering was used to assess fibre concentrations in small samples of tissue, while the optical microscope was applied to measure the severity of fibrosis in paraffin sections prepared from adjacent samples of the same specimens. Wide intra- and inter- subject variations were observed in fibre concentration and fibrosis score. When mass was used as the parameter of fibre quantity, the fibre concentrations in specimens showing a given degree of fibrosis increased progressively: Wittenoom < NW Cape < Transvaal < Paakkila. Significantly, however, when surface area was used as the parameter, the fibre concentrations in specimens showing a given degree of fibrosis were approximately equal: Wittenoom = NW Cape = Transvaal = Paakkila. But when number was used as the parameter, the fibre concentrations in specimens showing a given degree of fibrosis decreased progressively: Wittenoom < NW Cape < Transvaal < Paakkila. These trends in the concentrations of retained fibre required to produce the same degree of fibrosis are the consequence of large differences in fibre size between the four locations, rather than differences in type of amphibole. Long-resident chrysotile fibres exhibited roughly the same fibrogenicity per unit of surface area as amphibole fibres, and this was also true for quartz grains.

Distribution of choline acetyltransferase-, serotonin-, dopamine-beta-hydroxylase-, tyrosine hydroxylase-immunoreactive fibers in monkey primary auditory cortex.

Immunohistochemical methods were used to visualize choline acetyltransferase (ChAT)-, serotonin-, dopamine-beta-hydroxylase (DBH)-, and tyrosine hydroxylase (TH)-containing fibers in the primary auditory cortex of the cynomolgus monkey (Macaca fascicularis). Each antiserum revealed a subpopulation of axons with a distinct density and laminar distribution. ChAT-immunoreactive fibers were very dense in superficial layers, particularly in layers I, deep III, and IV, and very sparse in layers V and VI. No immunoreactive cell bodies were evident. Serotonin-immunoreactive fibers were very dense in all cortical layers but exhibited some subtle laminar differences in fiber size and orientation. The densities of DBH- and TH-immunoreactive fibers were substantially lower than the densities of both ChAT- and serotonin-immunoreactive fibers, particularly in layer IV. However, there were substantial differences between the distribution of TH-immunoreactive fibers and that of DBH-immunoreactive fibers. For example, the density of TH-immunoreactive fibers was substantially greater than that of DBH-immunoreactive fibers in layer I. In addition, TH-immunoreactive fibers differed from the other three systems in that TH-immunoreactive fibers exhibited a rostral to caudal gradient of decreasing density. This is the first characterization of the innervation of a specific cortical region by all four of these systems and the first detailed description of the cholinergic innervation of a primate neocortical region utilizing a specific anti-ChAT antiserum. These striking differences in density and laminar distribution suggest that the subcortical extrathalamic systems furnishing these axons differ significantly in their modulation of cortical auditory processing. These data extend observations of previous studies which revealed that the expansion and specialization of the primate neocortex is accompanied by a pronounced regional and laminar differentiation in the intracortical distribution of these highly divergent, extrathalamic afferents.

A histophysiological study of muscle differentiation and growth in the common carp, Cyprinus carpio Var. communis

From an histochemical and biochemical study on the fibre differentiation and muscle growth in common carp, Cyprinus carpio Var. communis, growth and development processes have been characterized on the basis of differences in fibre size, fibre number, lipid content, succinic dehydrogenase (SDH) and myofibrillar adenosine triphosphatase (m‐ATPase). A very early differentiation and zonal segregation of principal fibre types (red and white) and subsequent increase in muscle by their hypertrophy and hyperplasia was observed. These changes become pronounced after yolk sac absorption. The special character of the red muscle, as it develops from a superficial monolayered lateral sheet to a compact multicellular cone, was also investigated.

Effect of immobilization of short duration on the muscle fibre size.

In 10 patients with unilateral knee joint lesions, the injured leg was immobilized for 72 h by a plaster cast reaching from the hip to the ankle. At removal of the casts, open muscle biopsies were taken from the vastus medialis muscle on both sides. The muscle specimens were stained for myofibrillar ATPase activity and muscle fibre areas were measured on transverse sections. The differences in fibre size between the two sides were registered and statistically evaluated. The reduction in fibre size on the immobilized side was 14.4% for the type 1 fibres and 17.3% for the type 2 fibres, respectively. However, these differences were not significant because of considerable variations from case to case, with an increase in fibre size on the immobilized side in three cases. It is concluded that short time post-traumatic immobilization may have variable effects on the muscle fibre size and that one single biopsy might be insufficient to disclose early disuse atrophy whereas the method may be useful in cases of longer duration.

Variability of histochemical and morphometric data from needle biopsy specimens of human quadriceps femoris muscle

Duplicate needle biopsies from the lateral portion of quadriceps femoris muscle from 20 young, healthy males were investigated morphometrically and histochemically. Mean results showed both the size and occurrence of the three main fibre types present to be similiar to values obtained from a survey of the literature. However, considerable variations in the proportions of fibre types (coefficients of variation 30–40%) and significant ( P <0.001) differences in fibre size between individuals were common. Within individuals, comparisons of samples taken at a reference site in the right thigh with samples obtained from deeper, more proximal or contralateral sites also often showed significant differences in fibre size. These results suggest caution is necessary when interpreting apparent changes in such values derived from subsequent biopsies of individuals.

Development of the myotomal musculature in the red sea bream.

The developmental process of the myotomal musculature in the red sea bream was investigated histochemically from newly hatched larvae to juveniles, and histochemical characters of the fiber types were confirmed in young specimens. Three main fiber types, so-called red, pink and white, were recognized on the basis of differences in fiber size and the staining for SDH, NADHD, PhR and lipid. In addition to these three types, there were very small diameter fibers between the red and pink fiber zones, showing very weak or negative staining for SDH, NADHD, PhR and lipid. Newly hatched larvae were provided with a single layer of presumptive myoblasts of the superficial fibers surrounding the inner white fibrs. The myofibrils of superficial cells became evident by 2.9mm TL, and metabolic features referable to the red fiber type appeared in these cells prior to the first-feeding stage. At about 7mm TL, the pink fibers started to differentiate and the stratification of muscle fibers occurred in the red fiber zone, foreshadowing the definitive adult arrangement. The developmental process of the myotomal musculature seemed to be correlated with the swimming behavior of these larvae and junveiles.

Regional differences in fiber size in the cochlear nerve.

The topographical variations in fiber size in the cochlear nerve of cat were quantitatively studied by electron microscopy. Measurements of fiber size as they appeared at the outlet of the spiral lamina show that fibers originating from the basal part of the cochlea are larger than those from the apex. When the diameter of apical fibers and their axoplasms at two different levels are compared, a significant variation in size is observed. As they appear in the internal acoustic meatus the apical fibers are larger at the level of the nerve trunk compared with the same fibers near the ganglion cell bodies. There are significant differences in fiber diameter with regard to their length for fibers derived from the apical turn. These results are compared with previous findings.

Studies on the swimming musculature of the rainbow trout I. Fibre types

A histochemical study has been made on the myotomal musculature of the rainbow trout Salmo gairdneri Richardson. Four main types of fibre can be distinguished on the basis of differences in fibre size, lipid content and succinic dehydrogenase and myofibrillar adenosine triphosphatase activity (ATPase activity). Early histological studies have concluded that in addition to a superficial strip of muscle small diameter ‘red’ fibres occur throughout the trout myotome. These small diameter fibres occurring in the bulk of the myotome are shown to differ from the superficial fibres with respect to their oxidative metabolism and myofibrillar ATPase. The relevance of this finding to studies on the energetics and swimming efficiency of this species are discussed.

Data on fibre size in thirty-six human muscles: An autopsy study

The mean diameters of Type I and Type II fibres were calculated in 50 muscle sites in each of 6 previously normal male autopsy subjects. Type II fibres were found to be larger than Type I fibres in 44 out of the total of 50 sites, but in only 15 sites was the difference statistically significant. Of the 6 muscle sites in which the mean diameter of Type I fibres exceeded that of Type II fibres, only one statistically significant difference was recorded. Significant differences in fibre size did not seem to be related to muscle function in any way. Sampling multiple sites within one muscle revealed that the difference in the relative sizes of the two fibre types was greater in the deep areas than in the surface areas. The fibres of the medial head of gastrocnemius were found to be significantly larger than those of the lateral head; no such difference was found when the clavicular and sternal heads of pectoralis major and the lateral and medial heads of rectus femoris were compared. Both fibre types seemed equally variable in respect of fibre size and, because of the considerable differences between post-mortem subjects the normal ranges of fibre size calculated for individual muscles are correspondingly large. Since the majority of muscles showed no significant difference in the diameters of the two fibre types, it was thought probable that human muscles are adapted for their different physiological roles by means of their widely varying fibre type constitution and that fibre size is relatively unimportant in this respect.

Differences in fibre size of histologically processed pre- and post-rigor mouse skeletal muscle

Differences in fibre size of histologically processed pre- and post-rigor mouse skeletal muscle