Hypertrophy of the myometrial cells in women with myoma

A rapid growth of the uterus myoma results from the cell hypertrophy, which involves essential ultrastructural changes in the cytoplasm and the nucleus, thus suggesting the intensification cell functions. The increase in the cell volume and intensification of secretion is followed by the enlargement of the interface between the nucleus and the cytoplasm resulting in formation of numerous invaginations of the nuclear membrane. The autoradiographical data demonstrate a considerable DNA synthesis in the peripheral zone of the myoma, unlike the situation seen in the centre of the myoma and the unchanged myometrium, where DNA synthesis is not considerable. The cytospectrophotometric analysis confirms the above data showing the highest content of DNA in the peripheral zone of the myoma.     

Changes in the fluctuation of the contraction rhythm of spontaneously beating cardiac myocytes in cultures with and without cardiac fibroblasts

The heart functions as a syncytium of cardiac myocytes and surrounding supportive non-myocytes such as fibroblasts. There is a possibility that a variety of non-myocyte-derived factors affect the maturation of cardiac myocytes in the development of the heart. Cultured neonatal cardiac myocytes contract spontaneously and cyclically. The fluctuation of beating rhythm varies depending on the strength of coupling through gap junctions among cardiac myocytes, indicating that the development of intercellular communication via gap junctions is crucial to the stability of contraction rhythm in cardiac myocytes. In this study, we aimed at elucidating whether and how cardiac fibroblasts affect the development of cardiac myocytes from the point of view of the changes in the fluctuation of the contraction rhythm of cardiac myocytes in cardiac myocyte–fibroblast co-cultures. The present study suggested that cardiac fibroblasts co-cultured with cardiac myocytes enhanced the intercellular communication among myocytes via gap junctions, thereby stabilizing the spontaneous contraction rhythm of cultured cardiac myocytes.     

Possible involvement of ATP-purinoceptor signalling in the intercellular synchronization of intracellular Ca2+ oscillation in cultured cardiac myocytes

Isolated and cultured neonatal cardiac myocytes contract spontaneously and cyclically. The contraction rhythms of two isolated cardiac myocytes, each of which beats at different frequencies at first, become synchronized after the establishment of mutual contacts, suggesting that mutual entrainment occurs due to electrical and/or mechanical interactions between two myocytes. The intracellular concentration of free Ca(2+) also changes rhythmically in association with the rhythmic contraction of myocytes (Ca(2+) oscillation), and such a Ca(2+) oscillation was also synchronized among cultured cardiac myocytes. In this study, we investigated whether intercellular communication other than via gap junctions was involved in the intercellular synchronization of intracellular Ca(2+) oscillation in spontaneously beating cultured cardiac myocytes. Treatment with either blockers of gap junction channels or an un-coupler of E-C coupling did not affect the intercellular synchronization of Ca(2+) oscillation. In contrast, treatment with a blocker of P2 purinoceptors resulted in the asynchronization of Ca(2+) oscillatory rhythms among cardiac myocytes. The present study suggested that the extracellular ATP-purinoceptor system was responsible for the intercellular synchronization of Ca(2+) oscillation among cardiac myocytes.     

Fluctuations in the concentration of extracellular ATP synchronized with intracellular Ca(2+) oscillatory rhythm in cultured cardiac myocytes

Isolated and cultured neonatal cardiac myocytes contract spontaneously and cyclically. The intracellular concentration of free Ca²⁺ also changes rhythmically in association with the rhythmic contraction of myocytes (Ca²⁺ oscillation). Both the contraction and Ca²⁺ oscillatory rhythms are synchronized among myocytes, and intercellular communication via gap junctions has been considered primarily responsible for the synchronization. However, a recent study has demonstrated that intercellular communication via extracellular ATP-purinoceptor signaling is also involved in the intercellular synchronization of intracellular Ca²⁺ oscillation. In this study, we aim to elucidate whether the concentration of extracellular ATP changes cyclically and contributes to the intercellular synchronization of Ca²⁺ oscillation among myocytes. In almost all the cultured cardiac myocytes at four days in vitro (4 DIV), intracellular Ca²⁺ oscillations were synchronized with each other. The simultaneous measurement of the concentration of extracellular ATP and intracellular Ca²⁺ revealed the extracellular concentration of ATP actually oscillated concurrently with the intracellular Ca²⁺ oscillation. In addition, power spectrum and cross-correlation analyses suggested that the treatment of cultured cardiac myocytes with suramin, a blocker of P2 purinoceptors, resulted in the asynchronization of Ca²⁺ oscillatory rhythms among cardiac myocytes. Treatment with suramin also resulted in a significant decrease in the amplitudes of the cyclic changes in both intracellular Ca²⁺ and extracellular ATP. Taken together, the present study demonstrated the possibility that the concentration of extracellular ATP changes cyclically in association with intracellular Ca²⁺, contributing to the intercellular synchronization of Ca²⁺ oscillation among cultured cardiac myocytes.     

Contractile activity and cell-cell contact regulate myofibrillar organization in cultured cardiac myocytes

Adult feline ventricular myocytes cultured on a laminin-coated substratum reestablish intercellular junctions, yet disassemble their myofibrils. Immunofluorescence microscopy reveals that these non- beating heart cells lack vinculin-positive focal adhesions; moreover, intercellular junctions are also devoid of vinculin. When these quiescent myocytes are stimulated to contract with the beta-adrenergic agonist, isoproterenol, extensive vinculin-positive focal adhesions and intercellular junctions emerge. If solitary myocytes are stimulated to beat, an elaborate series of vinculin-positive focal adhesions develop which appear to parallel the reassembly of myofibrils. In cultures where neighboring myocytes reestablish cell-cell contact, myofibrils appear to reassemble from the fascia adherens rather than focal contacts. Activation of beating is accompanied by a significant reduction in the rate of total and cytoskeletal protein synthesis; in fact, myofibrillar reassembly, redevelopment of focal adhesions and fascia adherens junctions require no protein synthesis for at least 24 h, implying the existence of an assembly competent pool of cytoskeletal proteins. Maturation of the fasciae adherens and the appearance of vinculin within Z-line/costameres, does require de novo synthesis of new cytoskeletal proteins. Changes in cytoskeletal protein turnover appear dependent on beta agonist-induced cAMP production, but myofibrillar reassembly is a cAMP-independent event. Such observations suggest that mechanical forces, in the guise of contractile activity, regulate vinculin distribution and myofibrillar order in cultured adult feline heart cells.     

Fluctuations in the Concentration of Extracellular ATP Synchronized with Intracellular Ca2+ Oscillatory Rhythm in Cultured Cardiac Myocytes

Isolated and cultured neonatal cardiac myocytes contract spontaneously and cyclically. The intracellular concentration of free Ca²⁺ also changes rhythmically in association with the rhythmic contraction of myocytes (Ca²⁺ oscillation). Both the contraction and Ca²⁺ oscillatory rhythms are synchronized among myocytes, and intercellular communication via gap junctions has been considered primarily responsible for the synchronization. However, a recent study has demonstrated that intercellular communication via extracellular ATP‐purinoceptor signaling is also involved in the intercellular synchronization of intracellular Ca²⁺ oscillation. In this study, we aim to elucidate whether the concentration of extracellular ATP changes cyclically and contributes to the intercellular synchronization of Ca²⁺ oscillation among myocytes. In almost all the cultured cardiac myocytes at four days in vitro (4 DIV), intracellular Ca²⁺ oscillations were synchronized with each other. The simultaneous measurement of the concentration of extracellular ATP and intracellular Ca²⁺ revealed the extracellular concentration of ATP actually oscillated concurrently with the intracellular Ca²⁺ oscillation. In addition, power spectrum and cross‐correlation analyses suggested that the treatment of cultured cardiac myocytes with suramin, a blocker of P2 purinoceptors, resulted in the asynchronization of Ca²⁺ oscillatory rhythms among cardiac myocytes. Treatment with suramin also resulted in a significant decrease in the amplitudes of the cyclic changes in both intracellular Ca²⁺ and extracellular ATP. Taken together, the present study demonstrated the possibility that the concentration of extracellular ATP changes cyclically in association with intracellular Ca²⁺, contributing to the intercellular synchronization of Ca²⁺ oscillation among cultured cardiac myocytes.     

Electrical, contractile, and ultrastructural properties of adult rat and guinea-pig ventricular myocytes in long-term primary cultures

The electrical, contractile, and morphological characteristics of ventricular myocytes isolated from adult rat and guinea-pig hearts and maintained in cultures for 7-24 days are described. These cultured cells form different networks, depending on the species, when plated at certain density and maintained under specific conditions; the cells within the networks appear to be electrically coupled. Their resting and action potentials, their contractile activity (shortenings), and their pharmacological responses qualitatively resemble those of freshly isolated myocytes. Cultured cells from both species exhibit near-normal ultrastructural organization of sarcomeres, myofilaments, and mitochondria, as well as formation of intercellular contacts, or gap junctions. These data indicate that cultured adult rat and guinea-pig myocardial cells that make intercellular contacts possess electrical, contractile, and ultrastructural properties and responses to pharmacological agents similar to those of the respective adult myocardial tissues and the functionally intact freshly isolated cells from which these cultures are prepared. Thus, this study indicates that long-term cultures (7-24 days) of networked cardiac myocytes could be used as a valuable experimental model in various investigations of excitation-contraction coupling in cardiac muscle.     

Distribution and role of gap junctions in normal myocardium and human ischaemic heart disease

In the heart, individual cardiac muscle cells are linked by gap junctions. These junctions form low resistance pathways along which the electrical impulse flows rapidly and repeatedly between all the cells of the myocardium, ensuring their synchronous contraction. To obtain probes for mapping the distribution of gap junctions in cardiac tissue, polyclonal antisera were raised to three synthetic peptides, each matching different cytoplasmically exposed portions of the sequence of connexin43, the major gap-junctional protein reported in the heart. The specificity of each antiserum for the peptide to which it was raised was established by dot blotting. New methods were developed for isolating enriched fractions of gap junctions from whole heart and from dissociated adult myocytes, in which detergent-treatment and raising the temperature (potentially damaging steps in previously described techniques) are avoided. Analysis of these fractions by SDS-polyacrylamide gel electrophoresis revealed major bands at 43 kDa (matching the molecular mass of connexin43) and at 70 kDa. Western blot experiments using our antisera indicated that both the 43-kDa and the 70-kDa bands represent cardiac gap-junctional proteins. Pre-embedding immunogold labelling of isolated gap junctions and post-embedding immunogold labelling of Lowicryl-embedded whole tissue demonstrated the specific binding of the antibodies to ultrastructurally defined gap junctions. One antiserum (raised to residues 131–142) was found to be particularly effective for cytochemical labelling. Using this antiserum for immunofluorescence labelling in combination with confocal scanning laser microscopy enabled highly sensitive detection and three-dimensional mapping of gap junctions through thick slices of cardiac tissue. By means of the serial optical sectioning ability of the confocal microscope, images of the entire gap junction population of complete en face-viewed disks were reconstructed. These reconstructions reveal the presence of large junctions arranged as a peripheral ring around the disk, with smaller junctions in an interior zone: an arrangement that may facilitate efficient intercellular transfer of current. By applying our immunolabelling techniques to tissue from hearts removed from transplant patients with advanced ischaemic heart disease, we have demonstrated that gap junction distribution between myocytes at the border zone of healed infarcts is markedly disordered. This abnormality may contribute to the genesis of reentrant arrhythmias in ischaemic heart disease.     

The ultrastructure of the atrium in the adult newt Notophthalmus viridescens (Amphibia,Salamandridae)

The atrial wall of Notophthalmus viridescens is 25–75 μm thick and is trabeculated sparsely. Coronary vessels are absent. The endocardial endothelium is continuous and has 50–60 nm-wide fenestrae with diaphragms, rests on a discontinuous basal lamina and lacks occluding junctions. Cells found in the subendothelial connective tissue are xanthophores, melanophores, mast cells, fibroblasts, macrophages, and unmyelinated nerve fibers with Schwann cell investments. Epicardial mesothelial cells contain numerous 6–7 nm filaments and lamellar bodies which resemble myelin figures. Mesothelial cell junctions include maculae adhaerentes diminutae, desmosomes, and interdigitations. The epicardial connective tissue layer is more extensive than that of the endocardium, with xanthophores and melanophores rarely present and nerve fibers never observed. The myocardium consists of a mesh-work of myocytes 3–5 cell layers thick with little intervening connective tissue. Myocytes are 6–10 μm in diameter and have two or three peripheral myofibrillae. Typical A, I, H, Z, and M bands are present with a sarcomere length of 2.5 μm. T tubules are not observed. The sarcoplasmic reticulum has subsarcolemmal dilations. The nuclear pole region contains abundant mitochondria and atrial granules, extensive Golgi, and elements of smooth and rough-surfaced endoplasmic reticulum. Lateral intercellular junctions consisting of dense plaques, frequently continuous with Z-line material, are common. Oblique and transversely oriented junctions consisting of primarily of fascia adhaerentes, are present. It appears that amphibian atrial myocytes more closely resemble those of the amphibian ventricle than those of the mammalian atrium. Structural differences between amphibian atrial and ventricular myocytes seem to be quantitative rather than qualitative in nature.     

Lipid peroxidation and Ca2+,Mg2+-ATPase activity of uterine myocyte cell membranes in hyperplastic processes

It was shown that intensity of endogenous, Feascorbic- and NADPH-dependent lipids peroxidation in the border zone was 2-2.5-fold as higher as in the normal tissues. In the central part of the knot the intensity of all these above mentioned forms of lipids peroxidations is much lower than in the normal tissue. Plasma membrane Ca2+, Mg(2+)-ATPase activity of the border zone of myomic knot is 2-fold as lower as in the normal tissue. 10(-6) M malonal dialdegide decreases the Ca2+, Mg(2+)-ATPase activity up to the level of this enzyme activity in the border zone of myoma knot.     

Endothelium,the dynamic interface in cardiac lipid transport

Vascular endothelium is the dynamic interface in transport of lipid from blood to myocytes in heart and arteries. The luminal surface of endothelium is the site of action of lipoprotein lipase on chylomicrons and VLDL and the site of uptake of fatty acids from albumin. Fatty acids and monoacylglycerols are transported from the lumen in an interfacial continuum of endothelial and myocyte membranes. Lipoprotein lipase is transferred from myocytes to the vascular lumen, and is anchored there, by proteoheparan sulfate in cell membranes. Insulin, needed for synthesis of lipoprotein lipase and esterfication of fatty acids, is captured from the blood stream and delivered to myocytes by endothelial insulin receptors. Fatty acids, monoacylglycerols, lipoprotein lipase and insulin are transported along the same route, but by different mechanisms. The route involves the plasma membrane of endothelium and myocytes, the membrane lining transendothelial channels, and intercellular contacts. (Mol Cell Biochem116: 181–191, 1992)     

Reversible Inhibition of Gap Junctional Intercellular Communication, Synchronous Contraction, and Synchronism of Intracellular Ca Fluctuation in Cultured Neonatal Rat Cardiac Myocytes by Heptanol

We analyzed by Fotonic Sensor, a fiber-optic displacement measurement instrument, the effects of heptanol on synchronized contraction of primary neonatal rat cardiac myocytes cultured at confluent density. We also examined the effect of heptanol on the changes in gap junctional intercellular communication by using the microinjection dye transfer method, and on intercellular Ca²⁺ fluctuation by confocal laser scanning microscopy of myocytes loaded with the fluorescent Ca²⁺ indicator fluo 3. In addition, we studied expression, phosphorylation, and localization of the major cardiac gap junction protein connexin 43 (Cx43) using immunofluorescence and Western blotting. At Day 6 of culture, numerous myocytes exhibited spontaneous, synchronous contractions, excellent dye coupling, and synchronized intracellular Ca²⁺ fluctuations. We treated the cells with 1.5, 2.0, 2.5, and 3.0 mmol/liter heptanol. With 1.5 mmol/liter heptanol, we could not observe significant effects on spontaneous contraction of myocytes. At 3.0 mmol/liter, the highest concentration used in the current experiment, heptanol inhibited synchronous contractions and even after washing out of heptanol, synchronous contraction was not rapidly recovered. On the other hand, at the intermediate concentrations of 2.0 and 2.5 mmol/liter, heptanol reversely inhibited synchronized contraction, gap junctional intercellular communication, and synchronization of intracellular Ca²⁺ fluctuations in the myocytes without preventing contraction and changes of intracellular Ca²⁺ in individual cells. Brief exposure (5-20 min) to heptanol (2.0 mmol/liter) did not cause detectable changes in the expression, phosphorylation, or localization of Cx43, despite strong inhibition of gap junctional intercellular communication. These results suggest that gap junctional intercellular communication plays an important role in synchronous intracellular Ca²⁺ fluctuations, which facilitate synchronized contraction of cardiac myocytes.     

Morphology and distribution of cystic cavities in the normal murine thymus

Summary The normal murine thymus was examined by lightand electron microscopy to determine the distribution and morphology of extracellular cystic cavities. Most cavities were confined to the cranial half of each gland, situated at the junction between cortex and medulla. They varied in size and shape, and gave rise to narrow channels that coursed to the capsular surface of the gland. Large cavities could be divided into three zones. A short cranial zone exhibited gland-like features, consisting of cells lining a clear lumen. A central zone was lined by a diverse population of cells. Some possessed secretory granules, while others exhibited an apical ciliated border. Lining cells interdigitated with each other and were joined laterally by intercellular junctions. The lumen of the central zone contained lymphocytes and macrophages in an amorphous extracellular matrix. The caudal zone of each cavity had an attenuated and incomplete cellular lining, communicating directly with the surrounding thymic parenchyma. Thymic cavities may represent the initial part of the efferent lymphatic system of the gland, beginning in the tissue spaces at the corticomedullary junction. Selected cells could then enter and interact with the luminal contents in the central zone of the cavity. Ciliated cells may then propel lymphocytes and secretions into the narrow channels radiating from the uppermost part of the chamber, leaving a cell-free lumen in this region. These cavities may function in sequestering lymphocytes, macrophages and thymic secretions before their exit from the gland.     

Myocytes of the inguinal lymph nodes

Owing to the method for making total plane preparations of the capsule after A. V. Borisov, it is possible not only to prove presence of myocytes in the capsule and in the trabeculae of the inguinal lymph nodes in the man and rat, but to open out general regularities of their distribution and orientation. In the capsule areas, corresponding to the places, where the lymph nodules are adjacent to (zone A), the number of myocytes is the least. They are oriented in various directions and are in close contact with each other (fascicular-reticulate principle of distribution of myocytes). In the capsule areas, surrounding A zones (named B zones) the myocytes are situated in tight layers and have circulatory orientation. At the place where the afferent lymphatic vessel gets into the capsule, precapsular lymphangion makes an infundibular dilatation and its myocytes along the sloping spiral get into the capsule, where they are arranged circulatory and form a muscular "constrictor". While studying ultrastructure of myocytes in the rat inguinal lymph nodes, it has been found out that their structure is typical for the smooth muscle cells. There are numerous myo-myocytic contacts of nexus type, that unite the myocytes of the node into a single functional complex.     

On the Occurrence of Intracellular Blue-green Algae in Cortical Cells of the Apogeotropic Roots of Macrozamia communis L. Johnson

The occurrence of species of the cyanophytes Nostoc and Anabaenain the cortex near the algal zone is reported for apogeotropicroots of Macrozamia communis L. Johnson. Algae were found tooccur both intercellularly and intracellularly in cells of theinner and outer cortex. This is the first record of intracellularalgae in the cycads and only the second report of this phenomenonin vascular plants. By examination of cells at various stagesof invasion by algae, it is interpreted that algal invasionof cortical cells and intercellular spaces is preceded by mucusapparently secreted by algal zone cells of the host, and depositedin intercellular spaces of cortical parenchyma cells nearby.Also algal penetration of cortical cells is preceded by an algalinvasion front of finely granular mucal material which bypassesmucus already deposited in intercellular spaces and may eitherlyse part of the host cell wall or enter through the plasmo-desmata,filling much of the cell cavity. Subsequently, large numbersof the algal symbionts enter the cell and may be enclosed withinhost wall material. Electron microscopic techniques are nowbeing employed to further clarify these invasion processes.     

Redistribution of microtubules and pericentriolar material during the development of polarity in mouse blastomeres

The distribution of microtubules and microtubule organizing centers (MTOCs) during the development of cell polarity in eight-cell mouse blastomeres was studied by immunofluorescence and immunoelectron microscopy using monoclonal anti-tubulin antibodies and an anti-pericentriolar material (PCM) serum. In early eight-cell blastomeres microtubules were found mainly around the nucleus and in the cell cortex, whereas PCM foci were observed dispersed in the cytoplasm. During the eight-cell stage, microtubules disappeared from the area adjacent to the zone of intercellular contact and accumulated in the apical part of the cell while their number decreased in the basal domain. The PCM also relocalized to the apical domain of the cell, but this occurred after the redistribution of the microtubules by a mechanism that involved the microtubule network. The possible roles of both MTOCs and microtubules in establishing cell polarity are discussed.     

Structure and synaptic organization of the osphradium of the lamellibranch mollusk Unio pectorum

The osphradial organ has been studied in Lamellibranchia--Unio pectorum--by means of scanning and transmissive electron microscopy. On the surface of the distal part of this hemosensory organ there is a distinct division into zones. The central part of the osphradial torus is occupied by the receptory zone, formed predominantly by supporting cells with microvilli and by peripheral processes of the subepithelial receptory cells. The lateral surfaces are occupied with ciliar areas of the ciliar supporting cells. In the receptory zone two types of the peripheral processes of the receptory cells are identified; they differ by the number of kinocilia and by ultrastructural organization of the apical part. Axon-like processes of the receptory cells interact with axons and dendrites of the ganglionic cells, forming axo-axonal, axodendritic and axosomatic synapses. The facts revealed demonstrate a high level of specialization of the osphradial receptory surface, connected with polymodality of this organ.     

Peptidergic and monoaminergic innervation of the gonads in the holothurian Cucumaria japonica

In the holothurian gonad structure of the peptidergic and monoaminergic systems has been described. Axons of their cells form tissue and hemal terminals. Epithelial cells and smooth myocytes of the gonadal wall get direct innervation, having contacts with the axonal terminals that are separated by the cleft 50-75 nm in the diameter. It is possible that neuropeptides and biogenic monoamines are transported to the germ and follicular cells of the germinative gonadal zone via hemolymph of the hemal sinus.     

The epithelium of the middle ear in the guinea pig

Summary An electron microscopic study of aldehyde and osmium fixed normal guinea pig middle ear epithelium was made. Numerous branching microvilli occur between the cilia of the ciliated cells. The granules of the secretory cells are always surrounded by a membrane, and they vary in their content of electron dense substance. Half desmosomes are frequent in basal cells. The squamous epithelial cells of the bulla contain few microvilli and pinocytoric invaginations. In the basal part of the squamous epithelium dilations of the intercellular clefts often occur. The luminal part of the intercellular clefts are closed by multiple tight junctions.     

Immunohistochemical analysis of the adaptation of adult guinea-pig cardiomyocytes in long-term cultures and in cocultures with cardiac neurons: A novel model for studies of myocardial function

In this study, we used laser confocal scanning microscopy and immunofluorescent markers to describe the establishment of long-term cultures of adult guinea-pig cardiomyocytes and their cocultures with adult intrinsic cardiac neurons. We have also investigated the effect of plating density on the adaptation of the myocytes in culture. Providing that the preparation of freshly isolated cardiomyocytes consists mostly (> 80%) of rod-shaped, Ca-tolerant, and quiescent cells and these are plated under optimal conditions and density (105/cm2), these myocytes have the following characteristics: (1) they remain elongated with regular ultrastructural characteristics and quiescent for several days; (2) within 10-14 days, they reestablish their intercellular contacts and resume contractile activity, which becomes synchronous all through the confluent layers; (3) they retain their regular myofibrilar striation all through the adaptation to culture conditions without any sign of dedifferentiation or redifferentiation; (4) these characteristics are lost when the cells are plated at too low (< 104/cm2) or too high (2 × 105/cm2) a density and they exhibit signs of dedifferentiation; (5) the adult ventricular myocytes appear to retain their ability to express atrial natriuretic peptide (ANP), as indicated by immunoreactivity to anti-ANP antibody; (6) this activity seems to be directly related to the surface area of the myocytes in contact with the substrate (i.e. to the stretch of the myocytes); (7) the intrinsic cardiac neurons grow intricate networks of neurites, which form a free-ending type of contact with the cocultured myocytes.abstract typed in here; if it is more than one paragraph use Long-term cultures of adult guinea-pig ventricular myocytes, alone or in their cocultures with cardiac neurons in which both are fully active functionally, provide a valuable experimental model which opens new possibilities for studying the cellular and molecular regulation of myocardial function under acute or chronic effects of various intrinsic and/or extrinsic factors, including neuroregulation.