PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “fiber development”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1978

Histochemistry and acetylcholine receptor distribution in normal and denervated monkey extraocular muscles.

In monkey extraocular muscles (EOM), a battery of histochemical reactions delineates three muscle fiber types, coarse, fine, and granular. Normal EOM are compared with EOM denervated by intracranial oculomotor nerve section. The experimentally denervated EOM fibers did not show the constellation of histologic responses typical of denervated limb muscle, making a diagnosis of a denervation process in EOM muscle very difficult. Although the denervated fine and granular fibers (but not the coarse fibers) develop diffuse extrajunctional acetylcholine receptors (AChR) following experimental denervation, this is not a reliable criterion of denervation because not all of those fibers developed it and they did not show it beyond a 12-week period following nerve section; moreover, myopathic mechanisms have previously been shown capable of provoking diffuse extrajunctional AChR in limb-muscle fibers.

Acetylcholine↗
PubMed1976

Formation of myoneural and myotendinous junctions in the chick embryo. Role of acetylcholinesterase-rich granules in the developing muscle fibers.

The mode of formation of the myoneural and myotendinous junctions was investigated in the thigh muscles of the chick embryo. Myotendinous junctions first appeared on day 11 of incubation, whereas myoneural junctions developed on day 12. Intracellular AChE activity in the muscles increased by the 12th day of incubation, and decreased rapidly after the formation of the myoneural junctions. Light and electron microscopically, AChE activity was demonstrated in the nuclear envelope, sarcoplasmic reticulum, Golgi complex, and in large granules which appeared to be derived from the Golgi complex. Large granules showing an intense AChE activity accumulated in the sarcoplasm at the poles of the muscle fiber before the formation of myotendinous junctions. After the translocation of this intracellular enzyme onto the sarcolemma, most likely the result of an exocytosis of the granules, the myotendinous junctions were formed. The AChE-rich granules present in the middle of myotubes developed into spindle- or comma-shaped cisternae which were located in the sarcoplasm just below the presumptive motor endplates. The present results suggest that the transport of AChE-rich granules to the sarcolamma is the first step in the formation of myoneural and myotendinous junctions.

Acetylcholinesterase↗
PubMed1978

Sharpey fiber bone development in surgically implanted dog mandible. A scanning electron-microscopic study.

Ticonium metal implant placed surgically in the previously edentulatized adult dog mandible induced the formation of an extensive Sharpey fiber system. Sharpey's fibers extended from the peri-implant area, deep into alveolar bone. The frequency of Sharpey's fibers and the degree of their mineralization varied from scattered location and unmineralized state to heavy clustering and full mineralization. This study suggests that the formation of Sharpey's fibers and the degree of their mineralization are determined by biophysical forces of pressure received at a given site.

Alveolar Process↗
PubMed1987

Conduction properties of single nerve fibers in developing rat spinal nerve roots.

We have examined conduction properties and distribution of membrane currents in ventral spinal root axons of rats 12-47 days of age. Internodal length of the largest myelinated fibers increases at a steady 17-19 micron/day during this period as internodal conduction time decreases. Despite the rapid remodelling of fiber dimensions during the first few weeks of postnatal life, potassium channels are continually excluded from participation in action potential generation at the axon membrane of most nodes of Ranvier.

4-Aminopyridine↗
PubMed1975

Acetylcholine receptor turnover in membranes of developing muscle fibers.

[125I mono-iodo-alpha-bungarotoxin is used as a specific marker in a description of acetylcholine receptor metabolism. It is concluded that acetylcholine receptors in the surface membranes of chick and rat myotubes developing in cell cultures have a half-life of 22-24 h. Alpha-bungarotoxin (bound to a receptor which is removed from the membrane) is degraded to monoiodotyrosine which appears in the medium. Several observations are consistent with a model in which receptors or alpha-bungarotoxin-receptor complexes are internalized and then degraded: (a) the rate of appearance of iodotyrosine does not reach its maximal rate until 90 min after alpha-bungarotoxin is bound to the surface receptors; (b) 2,4-dinitrophenol, reduced temperature, and cell disruption all inhibit the degradation process. The degradation of surface receptors is not coupled to the process by which receptors are incorporated into the membrane. Evidence suggest that receptors are incorporated into the surface membrane from a presynthesized set of receptors containing about 10% as many alpha-bungarotoxin binding sites as does the surface. Additionally, a third set of acetylcholine receptors is described containing about 30% as amny binding sites as does the surface. These "hidden" recptors are not precursors yet are not readily accessible for binding of extracellular alpha-bungarotoxin. These findings are discussed in relation to both plasma membrane biosynthesis and control of chemosensitivity in developing and denervated skeletal muscle.

Animals↗
PubMed1975

[Clinical, electron-microscopic, and histochemical investigations of conjunctivitis lignosa (author's transl)].

A case is briefly described in which a typical conjunctivitis lignosa appeared after the eye had suffered lime burns. In order to help clarify the morphological connection between mucopolysaccharide production and fiber development in the tumor tissue which occurred after the burn, samples were examined histologically, histochemically and with the use of the electron microscope. The tumor had a cartilage like consistency. Its structure could be devided into three regions. Region A is the pseudo-membrane. It has root like extensions which anchor it to the underlying tissue, and which morphologically appear partially homogeneous and partially fibrous. Blood cells and cell remnants are included in the tissue of the pseudomembrane. The histochemical examination of the pseudomembrane did not present a uniform picture. Along with small amounts of dermatan-sulfate and chondroitin-sulfate B the membrane probably contained a rather large amount of hyaluronic acid. The pseudomembrane borders on a granular tissue (Region B) which is distinguished by the wide metachromatic sheathes of the blood vessels found in it and the particularly large number of active fibroblasts along its edges. The silver impregnation method and the electron-microscopic examination showed that the vascular sheathes consist of bundles of reticular fibers which constitute a three-dimensional network. A similar sort of sheath was observed around the fibroblasts. Chondroitin-sulfate makes up the largest fraction of the mucopoly-saccharides near the fibers and appears particularly concentrated at the intersections of the fibers, although it is also diffusely distributed as well. Dermatan-sulfate (or heparan-sulfate) is found only in the mucopolysaccharide sheath of the fibers themselves. The deep region of the tumor (Region C) consists almost exclusively of blood vessels, their sprouts and the fibroblasts which, with their wide fibrous sheathes, almost fill the spaces between the blood vessels. The reticular fibers and their mucopolysaccharide sheathes have the same structure as that observed in Region B, The fact that the mucopolysaccharides did not appear in plaques but rather as bound primarily to the fibers is grounds for suggesting that a fiber development disorder, probably stemming from the pericytes and fibroblasts rich in ergastoplasm and fibrilles, could play the principle role in conjunctivitis lignosa. The cartilagen like consistency of the tumor could be a result of the arrangement of the fibers and their mucopolysaccharide sheathes. Brief remarks are included concerning the therapeutic consequences of the study.

Adult↗
PubMed1975

[Demonstration of temporary multi-innervation of the cerebellar Purkinje cells by the ascending fibers during development in the rat].

The one-to-one relationship between cerebellar Purkinje cells and climbing fibres in the adult rats is the result of a regressive process affecting a multi-afferent pathway during the early post-natal period, as shown from the innervation by several independent climbing fibres of more than 50% of the Purkinje cells tested electrophysiologically on days 8 and 9.

Action Potentials↗
PubMed1990

Differential distribution of myosin isoforms among the myofibrils of individual developing muscle fibers.

Myosin was localized in situ in the posthatch chicken pectoralis using isoform-specific mAbs. The distribution among myofibrils was demonstrated by immunofluorescence and by immunogold EM. Fluorescein- or rhodamine-labeled antibody (12C5) specific for the head region (S1) of myosin was used as a marker to identify "embryonic" myosin. In longitudinal semithin frozen sections, a minority population of myofibrils stained intensely with 12C5. All other myofibrils in the same cell stained only weakly. Similarly, in Lowicryl-embedded ultrathin sections prepared for EM, a minority population reacted preferentially with gold-labeled 12C5. An antibody (5B4) specific for the rod portion of "neonatal" myosin reacted strongly with nearly all myofibrils, and this was evident by light and electron microscopy. A few of the fibrils that reacted strongly with 12C5 reacted weakly with 5B4. These observations demonstrate that an epitope reacting with 12C5 is more abundant in some myofibrils than in others within the same cell. Three categories of myofibrils can be identified by their relative proportions of embryonic and neonatal forms of myosin: in nearly all fibrils, a neonatal isoform predominates; in a minority population, embryonic and neonatal isoforms are both abundant; and in a few fibrils, an embryonic isoform predominates. It is concluded that there are distinct populations of myofibrils in which specific isoforms are segregated within an individual cell.

Aging↗
PubMed1991

Relationship of primary and secondary myogenesis to fiber type development in embryonic chick muscle.

The formation of fast and slow myotubes was investigated in embryonic chick muscle during primary and secondary myogenesis by immunocytochemistry for myosin heavy chain and Ca2(+)-ATPase. When antibodies to fast or slow isoforms of these two molecules were used to visualize myotubes in the posterior iliotibialis and iliofibularis muscles, one of the isoforms was observed in all primary and secondary myotubes until very late in development. In the case of myosin, the fast antibody stained virtually all myotubes until after stage 40, when fast myosin expression was lost in the slow myotubes of the iliofibularis. In the case of Ca2(+)-ATPase, the slow antibody also stained all myotubes until after stage 40, when staining was lost in secondary myotubes and in the fast primary myotubes of the posterior iliotibialis and the fast region of the iliofibularis. In contrast, the antibodies against slow muscle myosin heavy chain and fast muscle Ca2(+)-ATPase stained mutually exclusive populations of myotubes at all developmental stages investigated. During primary myogenesis, fast Ca2(+)-ATPase staining was restricted to the primary myotubes of the posterior iliotibialis and the fast region of the iliofibularis, whereas slow myosin heavy chain staining was confined to all of the primary myotubes of the slow region of the iliofibularis. During secondary myogenesis, the fast Ca2(+)-ATPase antibody stained nearly all secondary myotubes, while primaries in the slow region of the iliofibularis remained negative. Thus, in the slow region of the iliofibularis muscle, these two antibodies could be used in combination to distinguish primary and secondary myotubes. EM analysis of staining with the fast Ca2(+)-ATPase antibody confirmed that it recognizes only secondary myotubes in this region. This study establishes that antibodies to slow myosin heavy chain and fast Ca2(+)-ATPase are suitable markers for selective labeling of primary and secondary myotubes in the iliofibularis; these markers are used in the following article to describe and quantify the effects that chronic blockade of neuromuscular activity or denervation has on these populations of myotubes.

Animals↗
PubMed1976

Lateral motion of fluorescently labeled acetylcholine receptors in membranes of developing muscle fibers.

We have made direct, quantitative measurements of the lateral motion and age-dependent distribution of acetylcholine receptors (AChR) on the surface of rat myotubes in primary culture. AChR were fluorescently marked with tetramethylrhodamine-labeled alpha-bungarotoxin and AChR lateral motion was measured by the fluoresence photobleaching recovery technique. We found two coexisting distinct classes of AChR: (i) mobile, uniformly distributed AChR that appear on all myotubes shortly after fusion from myoblasts; and (ii) immobile, dense, highly granular AChR in patches of 10-60 mum size that appear shortly after fusion and disappear after myotubes have become extensively interconnected. In addition, evidence of turnover of AChR labeled with tetramethylrhodamine-alpha-bungarotoxin is seen in the gradual internalization of surface fluorescence within 36 hr after labeling. The relevance of these results to an understanding of the membrane dynamics and localization of muscle AChR is discussed.

Age Factors↗
PubMedDate not supplied

[Development of fiber endoscopes and some aspects of gastrointestinal endoscopy].

Clinical evaluation of the up-to-date fibre endoscope models makes it possible to set apart 3 successive stages in the course of creating gastro-intestinal endoscopy, viz. construction of instruments with side optics, making esophagofibroscopes with end optics and transformation of esophagofibroscopes into panendoscopes. Depending upon the nature of the disease and the diagnostic objectives to be fulfilled various types of fibre endoscopes, both new and old, are recommended for clinical use.

Biomedical Engineering↗
PubMed1976

[A functional-morphologic analysis of reactive changes in nerve fibers during development of collateral circulation in nerves].

After stopping the blood circulation along the femoral artery the collateral blood circulation is developing unevenly in different nerves. It depends on the architectonics of blood vessels of the zone. In time the intravenous anastomosis in the distal part of the ischiatic nerve sharply increases. It is pulsing and compressing the nerve bundles and may have a negative influence on nerve fibres. Reactive morphological changes of the axis cylinder, myelin incisions and Ranvier's constrictions are found in such a nerve. The analysis has shown that the changes noted have a character of local non-specific process accompanying physiological manifestations of parabiosis.

Animals↗
PubMed1990

Pulmonary elastic fibers in normal human development and in pathological conditions.

Normal human pulmonary elastic fiber development and development in some pathological conditions were examined using elastic stains by light microscopy, electron microscopy, and immunohistochemistry. In normal development elastic fibers, composed mainly of microfibrils, first appeared around primitive bronchioles at 10 weeks of gestation. As they matured, their appearance became more amorphous, and they extended into the peripheral alveolar walls. Development of elastic fibers was retarded in the hypoplastic lungs of the oligohydramnios syndrome, diaphragmatic hernia, and hydrops fetalis. Elastic development was also retarded in congenital pulmonary lymphangiectasia and in focal areas of lungs with pulmonary dysplasia. Distribution of well-developed elastic fibers was found around the dilated bronchioles and alveoli in cases of congenital cystic adenomatoid malformation and extralobar pulmonary sequestration. Elastic fibers were distributed irregularly and unevenly in the lungs of bronchopulmonary dysplasia and ventilated cases of Wilson Mikity syndrome. In addition, four very immature infants who had progressively deteriorating respiratory function showed an almost total lack of elastic fibers in their alveolar walls.

Chronic Disease↗
PubMed1989

Regional distribution of fiber types in developing baboon diaphragm muscles.

Fiber type distribution and mean fiber area were determined for seven sites in diaphragm muscles of premature (140 days gestation), full-term (180 days gestation), and adult baboons. Within a group, data did not differ significantly amongst the seven sites. The diaphragm of premature animals had a large proportion [56(+/- 2)%] of type IIc fibers, smaller proportions of type I, IIo, and IIh fibers [16(+/- 2), 21(+/- 1), and 7(+/- 2)%, respectively], and no type IIg fibers. Full-term animals had fewer type IIc [2(+/- 1)%] fibers, greater proportions of type I [46(+/- 2)%], IIh [23(+/- 1)%], and IIg [11(+/- 1)%] fibers, and a similar proportion of type IIo fibers [17(+/- 1)%]. Diaphragm from adult baboons had similar proportions of type IIh, IIg, and IIc fibers in females [39(+/- 4), 20(+/- 2), 1(+/- 1), 41(+/- 5), and 1(+/- 1)%] and males [48(+/- 2), 16 (+/- 1), 0(+/- 0), 36(+/- 2), and 3(+/- 2)%]. Fiber area for premature [143(+/- 9), 210(+/- 15), 231(+/- 15), and 156(+/- 16) microns2 for type I, IIo, IIh, and IIc fibers], newborn [317(+/- 32), 374(+/- 36), 468(+/- 42), 498(+/- 43), and 322(+/- 37) microns2 for type I, IIo, IIh, IIg, and IIc fibers], and for type I, IIo, IIg, and IIc fibers from adult female [1,759(+/- 130), 2,365(+/- 284), 5,026(+/- 742), and 1,843(+/- 111) microns2] and adult male [2,513(+/- 221), 3,987(+/- 267), 6,102(+/- 376), and 2,833(+/- 151) microns2] baboons indicated growth which correlated with body weight. Our results also show that metabolic and contractile enzymes develop normally, but growth of respiratory muscle fibers is arrested, during 10 days following premature birth.

Animals↗
PubMed1991

Origin of the ring muscle fibers in neuromuscular diseases.

Morphological histochemical and ultrastructural examination of the ring fibers in one case of myotonic dystrophy and one case of mitochondrial myopathy provides evidence that the ring fibers develop in the course of fiber splitting and reinnervation of muscle fiber fragments. The reinnervation may have been due to a neurogenic lesion coexisting in both cases with the myopathic picture. The histologically different type of annular myofibrils observed in one case of cap disease is probably due to delayed embryonic development and abnormal relations between the myofibrils and elements of the cytoskeleton.

Adenosine Triphosphatases↗
PubMed1976

Postnatal cytochemical development of muscle fibers in segmental tail muscles of the rat.

Postnatal development of extrafusal and intrafusal muscle fibers was examined histochemically in segmental tail muscles of the rat. At birth all fibers show a strong reaction for myosin ATPase, uniformity in diameter, and homogeneity in staining intensity. During the first postnatal week, the muscle fibers undergo gradual hypertrophy and hyperplasia but they all maintain the same intense homogeneous staining pattern for the enzyme. By day 9, further differentiation of the muscle fibers results in the formation of a second intrafusal fiber type while the extrafusal fibers are still relatively homogeneous. Finally, two kinds of extrafusal fiber and a third type of intrafusal fiber can be distinguished by day 21. This histochemical fiber pattern is essentially maintained in the adult. These findings show that fiber type development in rat tail muscles lags behind the usual time course of myogenesis known to occur in more rostral regions of the animal. It also indicates that histochemical differentiation of intrafusal fibers in these muscles does not parallel that which occurs in extrafusal fibers. It is likely that arrival and initial contact of sensory nerve terminals on developing intrafusal fibers at day 7 directly influences their relatively early histochemical heterogeneity.

Adenosine Triphosphatases↗