Muscular Elements Research Articles

Regulation of uterine activity during gestation and parturition in rabbits and rats.

Uterine muscular activity is influenced by ovarian steroid hormones, by nervous activity, and by endogenous, humoral or locally produced, uterus-activating agents such as the neurohypophyseal peptides, the prostaglandins, and various biogenic amines. Purely physical factors, such as stretch, also play a part in the regulation of myometrial function. While the neural control of uterine function is more intimately linked to uterine vascular supply than to its muscular elements, at least in rats and rabbits, the hormonal factors exert a profound influence directly on the contractile components of the uterus. However, in spite of much progress in recent years in the understanding of the mechanism of action of steroid hormones, the integration of biochemical events at the molecular level into various contractile responses at the tissue level remains to be elucidated. The possible interrelationship between endocrine factors and the nervous system in integrating the total activity of the whole organ has also to be clarified, but all evidence points to the hormonal and humoral agents as the dominating factors in the regulation of uterine contractility.

Crystalline style formation and function in the oysterCrassostrea gigas(Thunberg, 1795)

Abstract The crystalline style disappears from Pacific oysters held out of water, but is completely reformed 1 hour after submergence. The style is secreted and dissolved along its entire length and does not move forward into the stomach. It is renewed every 8 hours in submerged oysters or follows the tidal cycle in tidal localities. The style carries a thin superficial coating of mucus and food particles which travel its length in 50 minutes at 17°C. It is possible that the crystalline style functions by mechanically pressing nutritious particles against the absorptive epithelium of the style pouch and is a substitute for an almost total lack of muscular elements in the bivalve alimentary canal.

The ultrastructure of lymphatic valves in the adult rabbit lung.

An electron microscopic investigation has revealed that the pulmonary lymphatic valves of adult rabbits are not simple duplicatures of the lymphatic vessel wall. They consist of an uninterrupted central connective tissue core, covered on both sides with a single layer of flattened endothelial cells. Near their insertion in the lymphatic vessel wall, the connective tissue core reveals a distinct thickening being composed mainly of collagen bundles. In the other parts it contains mainly elastic fibers and fine filaments, enclosing also some rather peculiar connective tissue cells. Nervous and muscular elements were not observed. The endothelium is continuous and exhibits no open junctions. The valvular basement membrane is better developed than in lymphatic capillaries. The endothelial cells contain numerous cytoplasmic filaments which might be endowed with contractile properties. The nuclei of the endothelial and the connective tissue cells are irregularly spaced and frequently clustered near the free edge of the valve.

Fibromusculosis in chronic gastritis.

Seven‐hundred‐and‐sixty‐four stomachs from the Japanese and 456 from the Americans, both autopsy and surgical materials inclusive, were studied histologically. There were seen, within an unexpectedly large proportion of cases, distortion and thickening of the muscularis mucosae. This change consisted of a proliferation of fibrous and muscular elements. The incidence of the lesion increased with the advance of age reaching 77.4 per cent in the 6th decade in autopsy cases in the Japanese, whereas in the Americans it was less than 20.0 per cent, thus making a sharp contrast. Its association with classical gastritic changes was a usual occurrence. The term “fibromusculosis” was proposed by the author for the lesion, on the ground that it would constitute one of the important anatomical features of chronic “Umbau‐gastritis”

Musculature of the prostate gland.

SUMMARY The pattern of prostatic musculature may be outlined as follows: 1 The ureters enter the bladder, give rise to the trigonal musculature, and contribute elements to the bladder musculature. 2 The fibres of the trigonal muscle decussate in the midline and veer ventrally, giving rise to the internai sphincter and contributing fibres to the fibromuscular plate encircling the internai urethral orifice. 3 The internai sphincter surrounds the internai urethral orifice and decussates ventrally to the urethra, contributing elements to the urethra, external sphincter and prostatic parenchyma. 4 Henle's muscle arises from the puboprostatic muscle and in association with the external sphincter surrounds the urethra just distal to the prostate. It then passes ventrally and superiorly to insert into the glandular capsule of the prostate, the prostatic parenchyma and the tri go ne. 5 The ventral component of bladder musculature arises from the pubo-vesical ligament, the lateral true ligament of the bladder, and the fascial capsule of the prostate. The dorsal component arises from the glandular capsule of the prostate, the tendinous yoke under the uvula, and the prostatic parenchyma. 6 The longitudinal musculature of the urethra arises principally from the fibromuscular plate, but is also supplemented by elements from the glandular capsule, internai sphincter and prostatic parenchyma. 7 The double layered prostatic glandular capsule is contributed to by or gives rise to most of the muscular elements associated with the prostate gland, except the ventral longitudinal bladder musculature. 8 The external sphincter is formed by the distal prolongation of the anteriorly decussating fibres of the internai sphincter, and is separated from the deep perineal sphincter by the superior levator fascia. 9 The prostatic parenchymal musculature consists of ramifying septa extending between the middle third of the prostatic urethra and the prostatic glandular capsule. 10 Several prominent muscle groups envelop neuromuscular elements associated with the prostate gland and radiate into the adjacent supporting fascial structures.

Cortisol-induced malformation in an i vitro developmental model.

Extract: Morphologic effects of cortisol upon development were studied in an in vitro model in which populations of free mesenchymal cells, derived from embryonic mouse limb bud, form a heterogeneous tissue, and in five to six days develop characteristic cartilaginous and muscular elements (fig. 2). Development takes place in microwells with bases of a cellulose ester filter. Cortisol was incorporated into the culture medium at the concentrations shown in table I at various stages in culture (first to fourth day) and for variable periods of time (two hours to six days). The initial cell population density on the filter membrane was varied (table II). Cortisol concentrations of 1.4 × 10-5 M and 7.0 × 10-5 M for up to six days had no visible effects on formation of a tissue syncytium or subsequent differentiation. Concentrations of 1.1 × 10-3 M for longer than 48 hours led to death of the bulk of cells. Intermediate concentrations or shorter exposures were compatible with tissue viability but were associated with morphologic abnormalities. These abnormalities largely resulted from interference with cell aggregation, chondrogenesis and myogenesis. The formation of compact cellular aggregates was impaired by exposure to cortisol concentrations between 1.4 × 10-4 M and 1.1 × 10-3 M. Varying degrees of inhibition were seen, extending from moderate limitation of compact aggregate size, alteration in shape and loss of distinct aggregate margins to total substitution of loose clusters of cells for compact aggregates. The severity of effects was directly related to cortisol concentration and duration of exposure and inversely related to initial cell population density (table III). Later stages in the development of compact aggregates were inhibited when exposure began at some time after the first day. Neither inhibition of cell movement on the filter surface nor restriction in cell population by cortisol appeared to be major factors interfering with aggregation. When exposure was discontinued prior to three days, compact aggregation resumed. Chondrogenesis was totally inhibited by cortisol concentrations of 1.1 × 10-3 M for more than one day and partially inhibited by concentrations of 7.0 × 10-4 M and 3.5 × 10-4 M. In the latter instances, the effects varied with stage of exposure. Exposures for the first two or three days of culture resulted in fewer cartilage centers, confined mainly to the membrane center. Similar exposures during the last three days of culture restricted the size of cartilage centers but did not affect distribution on the filter surface; such exposures were associated with diminished intercellular metachromasia upon staining with toluidine blue. With exposure for the entire culture period, chondrogenesis was uncommon even at such lower concentrations. Myogenesis: was inhibited at concentrations of 2.0 × 10-4 M or greater. Exposure in the first two days of culture impaired bipolar transformation of myoblasts. Exposure at a later time inhibited multinucleated myoblast and myotube development and restricted the number of myogenic cells. Speculation: The present investigation demonstrates that structural anomalies can be produced by a glucocorticoid in an in vitro developmental model and their evolution observed. The model is suitable for studying features of abnormal development because of the simplified morphogenesis inherent in the system. It offers opportunities for varying not only the conditions of exposure but also the cell source. The degree of relevance of the model to the in vivo situation, however, remains to be identified.

Development of the myoneural junction in the rat.

The structure of the myoneural junction in the striated muscle of rat embryos and postnatal rats was studied by electron microscopy in order to assess at ultrastructural level the roles of neuronal and muscular elements and the sequence of events resulting in the formation of a functionally mature synaptic organization.

Phasic and tonic neuromuscular systems in the abdominal extensor muscles of the crayfish and rock lobster

1. 1. The histological and physiological features of the deep and superficial extensor muscles in the abdomen of the crayfish ( Procambarus) and rock lobster ( Panulirus) were investigated. 2. 2. The deep muscles consist entirely of rapidly contracting muscular elements which have the histological features of “phasic” muscle fibres. They have short (2–4 μ) sarcomeres and a uniform distribution of the myofilaments. In many cases adjacents parts in these muscles show electronic interaction. 3. 3. The superficial extensor muscles contract slowly and are histologically of the “tonic” type. The sarcomeres are relatively long (9–11 μ) and the myofibrils are grouped in clumps. 4. 4. From each segmental ganglion, the deep extensors receive four (rock lobster) or five (crayfish) excitor axons, and one inhibitor. Two of the excitors and the inhibitor send branches to the next posterior segment. 5. 5. The excitor axons typically produce large electrical responses, often spike-like, for each impulse. The responses fatigue readily with repeated stimulation. Post-tetanic potentiation of electrical and mechanical responses is often seen following a train of closely spaced impulses in certain of the axons. 6. 6. The excitor axons of the superficial extensor muscles give small junctional potentials which generally undergo facilitation with repeated stimulation and show little fatigue. 7. 7. The muscle fibres and axons of the deep muscles are adapted for phasic contraction, whereas the corresponding elements of the superficial muscles are adapted for tonic contraction.

ABDOMINAL AORTIC ANEURYSM WITH VENA CAVAL FISTULA. REPORT OF A CASE WITH OBSERVATIONS ON AN UNUSUAL CLINICAL COURSE.

By the fourth decade of life, when the intima of the aorta achieves histologic maturity, degenerative processes in the large arteries are already gaining momentum. These occur more in the aorta than in its smaller more muscular branches. The most significant change is a disruption of the elastica and to a lesser degree the muscular elements. There is subsequent displacement by less resistant collagen tissue and infiltration with calcific and atherosclerotic elements. This may result in aneurysmal dilatation and even rupture. 1 The increasing incidence of arteriosclerotic aortic aneurysm warrants a review of its diagnostic features and complications. Over 50% of such aneurysms will eventually rupture, 1 usually into the retroperitoneal space. Occasionally the aneurysm may rupture into the gastrointestinal lumen, most frequently the adjacent third portion of the duodenum. 2 Less often, the aneurysm may erode into the adjacent inferior vena cava and form an arteriovenous fistula. 3-6 Preoperative

Anatomic and Electromyographic Studies of the Costo-Pulmonary Muscles in the Cock

INTRODUCTIONTHE gross anatomy of the avian pulmonary diaphragm, with some speculation as to its function, has been described by a large number of investigators. Since a recent review of the literature concerning this structure has not been published and in view of the possible importance of this structure in the normal respiratory function in the bird, it is desirable to initiate this communication with a discussion of the observations of previous workers.The broad connective tissue sheet and the associated bundles of skeletal muscle which cover the ventral surface of the lungs of the bird have been termed the diaphragme pulmonaire by Sappey (1847), the diaphragmite anterieur by Milne-Edwards (quoted by Huxley, 1882), the pulmonary aponeurosis by Huxley (1882), and the pulmonary diaphragm by Müller (1907–08). Since the term “aponeurosis” is generally used to refer to a broad flat tendon and does not include any muscular elements, the…

INNERVATION OF THE BLOOD CAPILLARY IN THE HEART OF DOG AND RABBIT.

The fine innervation of the heart in dog and rabbit was investigated by the electron microscope. It was concluded that:1. Not only precapillary but also true capillary in the area of sino-atrial node of dog and rabbit are innervated by cholinergic and adrenergic nerve fibers.2. Two types of synaptic vesicles were identified, the one (cholinergic) has the average diameter of 500A, while the other (adrenergic) 1, 000A. The latter synaptic vesicles contain granules in the core. Dense granules in the core of the vesicles may be associated with catecholamine.3. Possible role of the synaptic vesicles to the true capillary without muscular elements was discussed briefly.

Assessment of Functional Competence in Isolated Muscular Tissues

IN order to test for functional competence in thin pieces of isolated tissue containing muscular elements, such as the skin of the rat (which contains smooth muscle and a sheet of skeletal muscle known as the panniculus carnosus)', a bath was devised in which the muscles could be excited directly or indirectly by transmural stimulation1. The response of the stimulated muscle provided a measure of functional competence in the surviving tissue. This bath and also our method of recording the pressure changes developed in it are described here.

Effect of oxygen inhalation on manual performance in the cold

The effect of oxygen inhalation on block-stringing performance of 12 subjects was studied at hand temperatures of 32.7 C in a control room environment of 29 C and after cooling the hands to 16.0 C in a cold (5 C) environment. A similar slight but significant improvement in manual performance accompanied oxygen inhalation under both conditions. This is interpreted as indicating the existence of suboptimal neural and/or muscular activity during air breathing in both situations. If hand cooling had affected the same neural and/or muscular elements as oxygen, lowering activity even further from the optimal level, this should have exaggerated the O2 effect. In view of the absence of such a response, it would seem that hand cooling and oxygen influence different neural and/or muscular elements, and their effects on manual performance are not directly related. Submitted on August 31, 1961

Differentiation in regeneration I. The development of muscle and cartilage following deplantation of regenerating limb blastemata of Amblystoma larvae

Six- to 15-day blastemata of regenerating forelimbs of Amblystoma larvae were deplanted to the dorsal fin region both with and without their stumps attached. With stump present the deplant regenerates developed skeletal and muscular elements of the limb. In the absence of stump tissues no blastema developed a musculature whereas blastemata of all ages gave rise to elements of the forelimb skeleton.

Roentgen diagnosis of fibromuscular hyperplasia of the renal arteries.

Fibromuscular hyperplasia of the renal artery has recently been reported as a cause of renal arterial stenosis and secondary hypertension in a small number of cases. Leadbetter and Burkland (2) first described the entity in a five-and-one-half-year-old Negro boy. DeCamp and Birchall (1) reported a case in a twenty-three-year-old male. McCormack et al. (3) added 3 examples but did not mention the sex of their patients. Poutasse and Dustan (5) described “fibrous intimal proliferation” in the renal artery of 2 young persons with hypertension but they, also, failed to designate the sex. Wylie and Wellington (6) pointed out characteristic features of fibromuscular hyperplasia of the renal artery in 3 patients and made reference to an additional 5 cases. The following report emphasizes the roentgen findings in 11 patients with fibromuscular hyperplasia of the renal arteries seen within a period of two years, including the cases described by Wylie and Wellington. Ten were investigated at the University of California Medical Center and 1 at the Veterans Administration Hospital, San Francisco, Calif. The patients were all females between fifteen and forty-nine years of age, with hypertension known to have been present one week to twelve years. The blood pressure elevation was mild in 1 case and moderate to severe in the remainder, with a preoperative range of 170/100 to 250/140. In 3 patients the hypertension was asymptomatic. All but 1 had an audible systolic bruit in the upper abdomen. To date 9 of the patients have been explored surgically. In each, the stenotic lesion in the renal artery or arteries was found to be due to hypertrophy of the muscular elements and, to a lesser extent, to the fibrous connective-tissue elements of the media of the vessels. Arterial reconstructive procedures were performed in all cases with the exception of 1 in which nephrectomy was done. Following operation, blood pressure returned to normal levels in 5 and decreased significantly, but not to normotensive levels, in 3 patients. Hypertension returned in 1 instance after an initial postoperative decrease in blood pressures; renal arteriography demonstrated development of further arterial stenosis. Roentgen Features Location: Unlike arteriosclerotic narrowings of the renal arteries, which tend to occur predominantly within the medial third of the vessel, fibromuscular hyperplasia appears to involve primarily the middle and/or distal third and may extend into the proximal branches of the main renal artery. In the present series the right renal artery alone was involved in 7 patients, both arteries in 3, and the left artery in 1. Appearance: In each instance the area of involvement presented a distinctive appearance on renal arteriography. The most common configuration is best described as a contrast-outlined image resembling a string of beads of varying size (Fig. 1, A and B).

Adenomyomatosis of the gall-bladder (intramural diverticulosis).

Adenomyomatosis is a hyperplastic condition of the epithelial and muscular elements of the gall-bladder wall. It is also known under many other names but that used here is preferred as it is descriptive and is noncommital as far as aetiology is concerned. The condition is not uncommon but for various reasons has been rather neglected in the past. It is thought to predispose to stone formation and cholecystitis but may be found without either. It is probably a degenerative condition, the incidence increasing with advancing age. There may be associated cholesterosis. The lesions are of three main types: generalised, segmental and fundal. The radiological features of these are described. The main diagnostic points are collections of contrast medium in the dilated Rokitansky-Aschoff sinuses around the main gall-bladder shadow, strictures, septa, kinks and filling defects. The condition may be diagnosed even when Rokitansky-Aschoff sinuses are not visualised. Concentration of opaque medium and contraction afte...

Reparative regeneration of skeletal muscle in mammals receiving vitamin B12

The author studied the effect of vitamin B12 on the reparative regeneration of skeletal muscle tissue in sexually mature male rats. A standard injury was inflicted on all the animals. In comparison with control animals reactive changes in the injured muscle were more pronounced in rats which received vitamin B12. These changes involved increased disintegration of one part of the muscle fibers situated at some distance from the wound, as well as progressive morpho-physiological reconstruction of a large number of muscle fibers with abundant formation of myosymplasts. In rats which received vitamin B12 the formation of young muscular elements was intensified owing to the active regenerative reconstruction of muscle fibers.

A Cineradiographic Study of Respiration in Myxine Glutinosa L

ABSTRACT The anatomy of the respiratory organs, as well as the mechanism of breathing in myxinoids, is distinctly different from that in all other fish-type craniotes even including the petromyzonts. In Myxine the branchial gill lamellae are enclosed in rounded sac-like pouches, with ducts conveying the water from the oesophagus to the gills from which it travels through efferent ducts uniting on each side, finally leaving the animal through paired branchial apertures. In addition to the paired gill pouches there exists an oesophago-cutaneous duct connecting the pharynx to the exterior behind the left, last gill sac. The exterior opening is confluent with the left gill pore. Regarding the course of the respiratory current in this system contradictory explanations have been presented. More recent authors seem, however, to agree upon the concept that the water current is solely dependent upon the pulsating activity of the velum and is not influenced actively by either the gill pouches or their ducts (Gustafson, 1935; Strahan, 1958; Marinelli, 1956). The velum and its connected muscles, which is a unique structure in myxinoids, was already anatomically described by Müller in his Myxine monograph (1835) and later by Fürbringer (1875) and Cole (1907). The first two authors, however, did not contemplate the velum as being of any functional value for respiration. Cole, on the other hand, suggested a role for this structure in the maintenance of the respiratory current. Goodrich (1930) has advocated that breathing in Myxine takes place by expansion and contraction of the muscular elements in the gill sacs. That the gill sacs in Myxine contain distinctly striated muscular elements has been described by Cole (1912) and later by Goodrich (1930) and Hofbauer (1937). It seems obvious, upon reviewing the literature, that the physiological interpretations of this problem in earlier works are mostly founded on anatomical studies with little or no physiological experimentation. The excellent works of Gustafson (1935) and Strahan (1958) base their functional interpretations entirely upon external observations of the living animal or upon dropping coloured solution in the respiratory water and following its course into the nostril and out of the branchial apertures. The present study attempts to analyse the mechanics of respiration in Myxine by utilizing modern cineradiographic equipment which allows fluoroscopic examination of all events inside the respiratory passages; these may be recorded on a camera at 26 frames per second. The method has been used earlier for the study of the circulation in snakes (Johansen & Hol, 1960) and of the central circulation in Myxine (Hol & Johansen, 1960).

CIRCULATION IN THE HAGFISH, MYXINE GLUTINOSA L

1. Electromanometers have been used to study the pressure relations in the vascular system of Myxine glutinosa L. 2. The data demonstrate a low arterial pressure level in this species correlating with the existence of a lacunar circulation. 3. The average pressure in the dorsal aorta ranged from 3-8 mm. Hg with a pulse pressure of around 25 mm. H2O. The average pressure drop across the gills, calculated from the average pressures in the heart ventricle and dorsal aorta, was found to be around 4 mm. Hg. 4. The gills have been shown to take active part in the forward propulsion of arterialized blood. This is accomplished by contraction of striated muscular elements in the gills and gill ducts. 5. It is concluded that the circulation in Myxine differs from circulation in vertebrates generally by a partial shifting of the blood-moving power from the systemic heart to the gills and the portal, cardinal and caudal auxiliary hearts.

Histochemical demonstration of acetylphosphate phosphatase in normal and dystrophic human muscle

A phosphatase hydrolyzing acetylphosphate which is magnesium-sensitive and which has the optimum activity at pH 7.0 has been demonstrated histochemically in human muscle. It is concluded that this enzyme is localized in the sarcoplasmic part of the muscle fiber. It is present in the connective tissue as well as in muscular elements. The activity of the enzyme is increased in both sites in progressive muscular dystrophy. Muscle and connective tissue nuclei show acetylphosphatase activity, and although this reaches its optimum at pH 7.0 it is not as sensitive to the absence of Mg as the sarcoplasmic enzyme.