Muscle Lamellae Research Articles

Unique Features of River Lamprey (Lampetra fluviatilis) Myogenesis.

The river lamprey (L. fluviatilis) is a representative of the ancestral jawless vertebrate group. We performed a histological analysis of trunk muscle fiber differentiation during embryonal, larval, and adult musculature development in this previously unstudied species. Investigation using light, transmission electron (TEM), and confocal microscopy revealed that embryonal and larval musculature differs from adult muscle mass. Here, we present the morphological analysis of L. fluviatilis myogenesis, from unsegmented mesoderm through somite formation, and their differentiation into multinucleated muscle lamellae. Our analysis also revealed the presence of myogenic factors LfPax3/7 and Myf5 in the dermomyotome. In the next stages of development, two types of muscle lamellae can be distinguished: central surrounded by parietal. This pattern is maintained until adulthood, when parietal muscle fibers surround the central muscles on both sides. The two types show different morphological characteristics. Although lampreys are phylogenetically distant from jawed vertebrates, somite morphology, especially dermomyotome function, shows similarity. Here we demonstrate that somitogenesis is a conservative process among all vertebrates. We conclude that river lamprey myogenesis shares features with both ancestral and higher vertebrates.

The Australian lungfish (Neoceratodus forsteri) - fish or amphibian pattern of muscle development?

The Australian lungfish Neoceratodus forsteri (Dipnoi-Sarcoterygians) is a likely candidate for the extant sister group of Tetrapoda. Transmission electron and light microscopy analysis revealed that the arrangement of somite cells of the lungfish resembles the structure of the urodelan somite. On the other hand, the pattern of early muscle formation in N. forsteri is similar to that found in the Siberian sturgeon (Acipenser baeri). During the early stages of myogenesis of N. forsteri, somite-derived cells fuse to form multinucleated muscle lamellae. During later stages, mononucleated undifferentiated cells are first observed in the intermyotomal fissures and subsequently in the myotomes, among white muscle lamellae. The cells from the intermyotomal fissure differentiate into fibroblasts. The cells which have migrated into the myotomes, differentiate into mesenchyme-derived myoblasts. After hatching, white muscle lamellae are successively converted into polygonal muscle fibres. Conversion of lamellae into fibres may occur through splitting of muscle lamellae, or cylindrical muscle fibres may arise de novo as a result of fusion of mesenchyme-derived myoblasts. No increase in the number of muscle fibre nuclei is observed either in embryonic or juvenile musculature of N. forsteri. We suggest that until the 53 stage of embryonic development, the increase in muscle mass is accomplished mainly through hyperplasy. Thus, lungfish muscle represents the organizational intermediate between fishes and amphibians. This makes it a useful model to study the evolutionary implications of the mechanisms of muscle development.

Immediate mamoplasty with pedicle graft of the pectoral major muscle lamella after nipple-preserved mastoctomy

目的 创立一种手术方式,改善保留乳头的乳癌根治术后患侧的外观状况.方法 19例适合条件的乳腺癌患者在保留乳头的乳癌根治术后,游离胸大肌中、内侧肌束并反转向下,衬垫于乳头和乳晕下,重塑其乳腺外形.结果所有患者的术后乳头乳晕由贴近胸壁变为凸起3～4 cm,具备较好的乳腺形态.结论带蒂胸大肌瓣反转移植术对于保留乳头的乳癌根治术后乳头的三维偏移,将发挥重要的矫正作用。

Myotomal myogenesis of axial muscle in the sturgeon Acipenser baeri (Chondrostei, Acipenseriformes)

Compared to teleost fishes, a unique character of the myogenesis of the plesiomorphic A. baeri is the fusion of myoblasts derived from the somite, leading to the formation of multinucleate muscle lamellae. Then, the lamellae are converted into cylindrical muscle fibres. The mechanism of transformation of lamellae into fibres is still debatable. Early embryonic muscle growth is mainly due to the hypertrophy of somite-cell derived stock. After hatching, hypertrophic growth occurs parallel to hyperplastic growth. Proliferatively active mesenchymal cells, which migrate from the intermyotomal space into the myotomes, participate in both processes.

C-kit immunoreactive interstitial cells of Cajal in the human small and large intestine.

c-kit immunohistochemistry was performed on unfixed frozen sections of human small (duodenum, jejunum, and ileum) and large intestine (ascending, transverse, descending, and sigmoid colon). The c-kit immunoreactive cells in the muscularis externa of the intestinal wall were identified as interstitial cells of Cajal (ICC) and mast cells. ICC were identified by their morphology, localization, and organization based on previous light and electron microscopic studies. In the small intestine, ICC were located primarily in relation to the myenteric plexus of Auerbach, but also in septa between circular muscle lamellae. In the large intestine, ICC were seen in relation to Auerbach's plexus, but also and in great numbers in the circular muscle layer and in teniae of the longitudinal muscle layer. The morphology of the ICC was similar in the small and large intestine, but the pattern of distribution was obviously different. c-kit immunoreactive mast cells were found predominantly in the inner part of the circular muscle layer. The anti-c-kit method is found to be an easy and reliable method to study at least most of the interstitial cells of Cajal and thereby contribute to further normal and pathological studies.

Circular muscle lamellae of canine colon are electrically isolated functional units

The circular muscle (CM) layer of canine colon consists of circumferentially oriented lamellae separated by connective tissue septa. These lamellae facilitate circumferential ring contractions. Communication between CM lamellae is necessary to generate coordinated, propulsive phasic contractions to create peristaltic movement. Potential roles of the submuscular network of interstitial cells of Cajal and branching smooth muscle cells (ICC-bSM), the myenteric interstitial cells of Cajal network (ICC-AP), and the longitudinal muscle (LM) layer in mediating communication between the CM lamellae were studied by simultaneously recording with three surface electrodes, using different types of muscle strip preparations. When the ICC-bSM network was intact, slow waves were observed to be entrained both along and across CM lamellae. In contrast, the CM layer devoid of the ICC-bSM network, the myenteric plexus, and the longitudinal muscle (CM preparation) was spontaneously quiescent. Spike-like action potentials, evoked in the CM preparations by Ba2+ (0.5 mM), were entrained within CM lamellae but were not coordinated between the CM lamellae. In the LM-CM preparations, in which the longitudinal muscle and the ICC-AP network were intact, the Ba(2+)-evoked action potentials were again not coordinated across septa but entrained within CM lamellae. In a step preparation, in which the ICC-bSM network was removed from part of the muscle strip, slow waves were observed to be entrained in areas with and without the ICC-bSM network when electrodes were positioned along septa. When electrodes were positioned across CM lamellae, synchronized slow wave activity was observed only in areas with the intact ICC-bSM network and quiescent activity was recorded in areas devoid of the ICC-bSM network. These results demonstrate that CM cells are electrically coupled within a CM lamella, but not between CM lamellae. The submuscular ICC-bSM network, but not longitudinal or circular muscle cells, nor the ICC-AP, mediates communication between CM lamellae.

Circular muscle lamellae of canine colon are electrically isolated functional units

Circular muscle lamellae of canine colon are electrically isolated functional units

A new theory of micturition and urinary continence based on histomorphological studies. 2. The musculus sphincter vesicae: continence or sexual function?

Results of a histomorphological study of serial sections carried out in frontal, transversal and sagittal directions in 65 bladder necks are presented. It is shown that the trigonal system of the urinary bladder consists of two anatomical structures: first, of a muscle originating from the muscle system of both ureters and converging to form within the bladder the interureteric ridge, the musculus interuretericus and of a second structure forming the actual trigonum vesicae. It is the musculus sphincter trigonalis or musculus sphincter vesicae. This muscle elliptically embraces the internal urethral orifice and is only formed by one muscle lamella. It does not as has often been described extend in any form to the urethra or to the surroundings. The so-called Bell muscle does not exist. During the reproductive years the lower part of the sphincter trigonalis is strongly pervaded with prostate tissue. This could enable the muscle to have a double function: a continence function in accordance with a consequent distinction between the urinary bladder and the urethra as urinary and sexual tract, and during ejaculation the muscle could prevent the retrograde ejaculation and on the other hand the contraction of the muscle could lead to the release of the prostate secretion.

Ultrastructure of interstitial cells of Cajal in circular muscle of human small intestine

Background: Interstitial cells of Cajal (ICC) may be important regulatory cells in gut muscle layers. This study examined ICC within the circular muscle of human small intestine. Methods: Surgically resected, uninvolved intestine was studied by light microscopy and electron microscopy. Results: Muscle lamellae were separated by main septa in continuity with submucosa. Smooth muscle cells ran radially in the septa. Two types of ICC were distinguished. One ICC type had abundant intermediate filaments and smooth cisternae and a discontinuous basal lamina. This ICC type was present in the septa and in the outer third of the circular lamellae. The other ICC type had a complete basal lamina and conspicuous caveolae. This ICC type was observed only in the inner third of the circular lamellae. Both ICC types were close to nerves, but only the latter type formed gap junctions with one another and with muscle cells. Junctions between the two ICC types were not observed. Conclusions: The arrangement suggests that ICC and radially oriented muscle cells participate in electrical and mechanical coordination of the circular muscle layer of human small intestine.

Summertime and early autumn activity of some enzymes in the carbohydrate and fatty acid metabolism of the crucian carp

In June, July, and September the activities of five enzymes involved in the carbohydrate and fatty acid metabolism, namely phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS), cytochrome oxidase (cyt ox) and 3-hydroxy-acyl-CoA dehydrogenase (HAD), were measured in the heart, liver, red muscle, white muscle, and gill lamellae of crucian carp (Carassius carassius). LDH activity was measured in both reducing (LDHr) and oxidizing (LDHo) directions.The PFK activity in red and white muscle increased significantly between July and September indicating a preparation to winter anoxia by an increased glycylytic capacity in these organs. The HAD activity of the liver had increased significantly (by more than 50%) by September, also a preparation to winter anoxia as HAD is used in the reversed β-oxidation (chain elongation of fatty acids). The LDHr and cyt ox activities in the heart and white muscle were highest in July. This shows that both the anaerobic and aerobic capacities are elevated in mid-summer when water temperature is high and oxygen concentration of the water could fluctuate greatly. The LDHo and CS activities in gill lamellae were lowest in July. The results show that the metabolism of crucian carp is under seasonal influence and that a preparation to winter hypoxia/anoxia could be detected in September.

Asymmetry of consequences of drug disposition mechanisms in the wall of the rabbit aorta.

SUMMARY The contraction elicited by norepinephrine (NE) and histamine (H) in the rabbit aortic strip occurs after a shorter latency and increases at a higher initial velocity to a greater steady state level when drug entry is limited to the intimal compared with the adventitial surface. Differences in the steady state contraction, but not in latency or initial velocity, disappear when intramural disposition pathways of the two agonists are blocked pharmacologically by deoxycorticosterone and a combination of iproniazid and 17-/?-estradiol, respectively. These and other observations are consistent with the hypothesis that inner vascular smooth muscle cells respond more than outer cells to submaximal concentrations of NE and H, an explanation that accounts for the persistence of differences in latency and initial velocity of response after disposition blockade. Although the effectiveness of disposition mechanisms in reducing agonist concentration may be uniform through the aortic medial thickness, because of differences in muscle sensitivity, the consequence of disposition on the contractile response to agonists entering through the adventitia would be greater than that through the intima. Thus, disposition mechanisms in the outer smooth muscle lamellae provide a functional barrier to susceptible agonists entering through the outside vessel wall surface. Circ Res 46: 22-28, 1980

The sarcoplasmic reticulum and associated plasma membrane of trunk muscle lamellae in Branchiostoma lanceolatum (pallas). A transmission and scanning electrom microscopic study including freeze-fractures, direct replicas and x-ray microanalysis of calcium oxalate deposits.

The trunk muscle lamellae of Amphioxus is made up of cross-striated lamellae about 1 μm thick. Transverse tubules are absent, but numerous subsarcolemmal vesicles are found in both tissue blocks and minced samples after aldehyde and osmium fixation, embedding and sectioning.

Electron microscopic studies on the myotomes of larval lamprey, Lampetra japonica.

Myotomes of the caudal one-third of the body of 26-day-old larval lampreys, Lampetra japonica, were studied by electron microscopy. Each myotome consists of horizontally stacked muscle lamellae. The myotomes are covered laterally by a single layer of flattened cells called here "lateral cells", and the other aspect is covered by an external lamina. The myotomes are midsegmentally innervated. Each muscle lamella usually contains two single cortical layers of myofibrils along the dorsal and ventral sarcolemma with a nucleus and mitochondria interposed between two layers. Numerous peripheral couplings are observed with relatively less developed triads. There are no membrane specializations to connect adjacent muscle lamellae within a myotome. Intermyotomal junctions are, however, noted between tips of cytoplasmic processes of muscle lamellae of adjoining myotomes. They resemble tight or gap junctions. No myofibrils are present in these cytoplasmic processes. Myotendinous junctions, with "terminal couplings" (Nakao, '75), are seen under development at the myoseptal ends of muscle lamellae. Lateral cells contain only ordinary organelles and no special structures such as myofibrils are found in the cytoplasm. They are connected to each other and to muscle lamellae by primitive desmosomes. They generally have no external lamina investment.

An electron microscopic study of the neuromuscular junction in the myotomes of larval lamprey, Lampetra japonica.

The neuromuscular junction in the myotomes of larval and adult lampreys, Lampetra japonica, was studied with the electron microscope. In larval lampreys of 26 days after artificial insemination, the myotome consists of triangular lamellae of muscle cell with their bases laterally and apexes medially oriented and placed one on the other. The lateral aspect of the myotome is covered by a layer of flattened cell, and the other aspect is covered by an external lamina which does not extend into the intercellular space between adjacent cells within a myotome. A bundle of thin axons was found in a depression at the middle of medial edge (apex) of each muscle lamella of the myotome and neuromuscular junction was formed here. No nerve endings were found at the myoseptal ends or at the lateral borders of the muscle lamellae. Enlarged axon terminals contained numerous clear vesicles with a few cored vesicles, mitochondria and neurofilaments. The presynaptic axolemma was separated from the postsynaptic sarcolemma by an interspace (50-55 mmu wide) with an interposed external lamina. In the trunk musculature of adult lampreys, nerve endings were found on the surface of the parietal fibers whereas they were seen on both the myoseptal ends near the myotendinous junction along the medial border of each central fiber. Thickening and enhancement in the electron density and accumulation of filamentous material on the sarcoplasmic surface of the postsynaptic sarcolemma were noted in both the larval and adult lampreys. Any other specific alterations were not found on both the pre- and postsynaptic membrane in the neuromuscular junctions of larval and adult lampreys. A brief comment was made on the relationship in development of the characteristic muscle units and patterns of the motor innervation in the larval and adult lampreys. The significance of the neuromuscular junction in the very young larvae reported here was also discussed in respect to the evolution of the neuromuscular junction, particularly in lower chordates, and it was presumed to be the most primitive pattern of innervation in the vertebrate skeletal muscle.

Ultrastructural and acetylcholinesterase studies on the innervation of the ductus arteriosus, pulmonary trunk and aorta of the fetal lamb

Ultrastructural and acetylcholinesterase (AChE) studies have revealed that the media of the fetal lamb ductus arteriosus, pulmonary trunk, and aorta are composed of alternate layers of concentrically arranged smooth muscle cells and connective tissue elements. The connective tissue layers composed mainly of collagen and elastica also contain blood vessels, leukocytes and mast cells and are looser than that present in adult elastic vessels. “Close contacts” are present between muscle cells in the same and some adjacent layers and are considered to provide a pathway for the spread of impulses between muscle cells. Large bundles of AChE-positive nerve fibers and small ganglia were seen in the adventitia. Smaller nerve bundles were seen extending into the outer third of the media where they were present in both the muscle and connective tissue lamellae. Nerve fibers were separated from muscle cells by a distance of from 2 μ to 75 A. On the basis of their intra-axonal vesicles, especially the small granular vesicles (600–800 A) and their AChE activity it seems likely that both adrenergic and cholinergic nerves are present in these vessels.

Structure of the segmental trunk muscle in amphioxus

Light and electron microscopy of the segmental trunk muscle in amphioxus demonstrate at least two types of muscle fibre or muscle lamella.