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At least 19 recordsLinked to original sources
PubMedDate not supplied

[The three-dimensional structure of the tunica intima and tunica media of the human fetal aorta studied by a new method].

A new method is developed for revealing the latent surfaces in the structure of organs by scanning electronic microscopy. The method is based on the treatment of specimens with potassium ethoxide until cells start to appear in the dissociating solution. Using this method, thoracic aorta of nine human fetuses at the stage of 20-28 weeks was studied. Subendothelial intima and media of human fetal aorta contain smooth muscle cells differing by their arrangement, shape and surface microrelief. The intima cells are arranged in a mosaic pattern formed of single cells or cell clusters. By means of cell processes they are connected with each other, as well as with endothelial and smooth muscle cells of the media. Smooth muscle cells in the inner part of the media also have processes and form an open network. Part of the cells penetrate the intima through pores of the inner elastic membrane. In the deeper layers of the media, laterally adjoining spindle-shaped smooth muscle cells are found. It is suggested that the observed cell polymorphism is due mostly to penetration of the media smooth muscle cells into subendothelium and modification of their shape under the effect of the microenvironment.

Aorta, Thoracic↗
PubMed1992

[Protection of the tunica intima during preservation of venous bypass grafts from harvesting to implantation].

The patency-rate of venous bypasses depends--beside other important factors--upon the integrity of the transplanted vessel, especially on the condition of the tunica intima. We investigated two different methods of venous storage and their on the intima. We examined 24 segments of healthy human saphenous vein and 65 segments of the inferior vena cava in the rat which had been harvested using a minimal touch technique. The veins were stored in the patients own arterial heparinized blood vs. Euro Collins solution at 4 degrees C, 20 degrees C and 37 degrees C over 15, 30, 60, and 90 minutes. As a reference we examined 11 segments of human saphenous vein which had been fixed immediately after harvesting. The stainings were performed with PAS, HE, Domagk-Elastica, and Toluidine-blue. We examined 1,181 slices by light-microscopy and used a damage score table for the documentation of the vein-trauma. No significant differences were found between human and animals veins. In the control-group the endothelium, the subendothelial layer, and the intern elastic membrane were intact in 57%, 78%, and 38%. At 4 degrees C the endothelium was intact in 31% having been stored in blood, and in 44% at Euro Collins solution. For the subendothelial layer the ratio was 48%/66%, and for the intern elastic membrane 26%/42%. At 20 degrees C we found a ratio of 55%/47% vs. 65%/58% vs. 37%/39%, and at 37 degrees C 56%/37% vs. 64%/51%/32%/38%. The factor time could be neglected up to 90 minutes. The results show that veins should be used immediately after harvesting.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[A comparative ultrastructural and morphometric analysis of the smooth myocytes in the tunicae intima and media of the human fetal aorta].

Transmission electron microscopy was used for studying the thoracic part of the aorta of 9 human fetuses of 20-28 weeks of development. In the medial tunic of the human fetus aorta there are smooth myocytes (SM) of the contractile and synthetic phenotypes. The latter are localized mainly in the inner part of the media. In the inner tunic there are also SM of the synthetic phenotype. With the help of processes they make contacts with endotheliocytes and processes of SM of the media. In the gaps between the subendothelial SM and endothelium there are particles of elastin which form the structure resembling an additional elastic membrane. It is reasonable to think that the migration of SM into the intima is a stage of normal development of the vessel associated with the adaptation to local hemodynamic conditions rather than an initial manifestation of atherosclerosis.

Aorta, Thoracic↗
PubMed1994

Changes in morphology of elastin fibers during development of the tunica intima of monkey aorta.

The normal development of elastin fibers in the thoracic aorta was studied in fetal, young, and adult monkeys. Tissue was examined by scanning electron microscopy (SEM) after NaOH treatment and by transmission electron microscopy (TEM). The NaOH treatment of fixed tissues effectively removed collagen fibers and enabled three-dimensional visualization of the elastin fibers. In intact fetal aortae, the internal elastic lamina (IEL) was situated immediately beneath the endothelium. This IEL consisted of superficial, longitudinally arranged bundles of elastin fibrils and an underlying solid sheet containing round fenestrations. In neonates, diffuse intimal thickening was observed. In the young and young-adult monkeys, the aortae exhibited intimal thickening with slender but split IEL. One of the most important findings of this study was that elastin fibers in the intimal thickening, as well as smooth muscle cells, ran in a longitudinal fashion. This was in contrast with the elastic laminae of the media which were mainly oriented circumferentially. Subendothelial elastin fibers in this intimal thickening combined with longitudinally arranged microfibrils which formed close associations with endothelial stress fibers. In some adult monkey aortae with well-developed intimal thickening, a complex meshwork of slender elastin fibers was also found beneath the endothelium. The development of the intimal elastin fibers is discussed in relation to hemodynamic forces.

Actin Cytoskeleton↗
PubMed1998

The differential distribution of hyaluronic acid in the layers of human atheromatic aortas is associated with vascular smooth muscle cell proliferation and migration.

Vascular smooth muscle cells (VSMC), under conditions of induced proliferation, similar to those involved in atherosclerosis, secrete an acidic glycan, 82% of which exhibits structural homology with hyaluronic acid (HA), has a molecular mass of 340 kDa (HA-340) and inhibits VSMC proliferation in vitro. In this study, the expression of glycans was investigated in human atheromatic aortas and evidence is presented that a HA molecule, similar to HA-340, is distinctly expressed in all aortic layers. The isolation of the glycans from human aortas was performed after homogenization of the individual aortic layers (atheromatic plaque, tunica intima, tunica media and tunica adventitia), by lipid extraction and extensive digestion with pronase and DNase. The total glycans were purified from the digestion products by gel filtration on Sephadex G-25 and fractionated on a Superose 6 column. Enzymatic treatment of the ensuing glycan fractions with all known glycosaminoglycan-degrading enzymes, followed by electrophoresis on polyacrylamide gradient gels and cellulose acetate membranes, revealed that, in addition to HA, the tunica intima and the atheromatic plaque also contained dermatan sulfate, while the tunica media and the tunica adventitia also contained chondroitin sulfates and heparan sulfate. The highest concentration of the human aorta HA was found in the tunica media, exhibiting a negative concentration gradient from the tunica media to the atheromatic plaque. Investigation of the biological function of the human aorta HA revealed that this molecule acts as a negative regulator on the PDGF-induced VSMC proliferation and as a positive regulator on the PDGF-induced VSMC migration. The differential expression of HA within the aortic layers correlates with the biological function attributed to this acidic glycan and associates it with key events in the progression of atherogenesis.

Adult↗
PubMed1984

Histologic examination of selected areas of canine pulmonary arteries.

Selected areas of pulmonary arteries from 18 healthy mixed-breed dogs were examined using histologic staining techniques. Smooth muscle cell, collagen, and elastin content of the tunica intima and tunica media were assessed. Fifteen dogs had abnormalities of tunica intima or tunica media in at least one arterial section examined. Of all arterial sections examined, 40% had histologic changes of the tunica intima or tunica media, and 42% of these vascular lesions were in the main pulmonary artery. The most commonly occurring pathologic change was loss of smooth muscle cells and elastin of the tunica media and replacement by collagen. This lesion is similar to cystic medionecrosis of the aorta. Seemingly, a high frequency of spontaneous vascular lesions exist in pulmonary arteries of young dogs.

Animals↗
PubMed1990

The aortic wall: an in vitro study of the double-line pattern in high-resolution US.

An in vitro study of macroscopically normal aortas from human cadavers was performed with high-resolution ultrasound (US). Rectangular pieces of 10 fresh aortas were submerged in saline solution and scanned from the intimal side. On US images a characteristic double-line pattern, consisting of an inner and an outer echogenic line separated by a relatively hypoechoic line, was seen. This configuration was initially interpreted as tunica intima, tunica media, and tunica adventitia. The thickness of each layer on the US images was measured by means of a computer-assisted procedure and on histologic specimens was measured by means of stereomicroscopy. The correlation between the two measurements was poor. Experiments in which intima and part of the media were removed did not change the US appearance. Plexiglas, metal plates, and plastic foil showed a similar double-line pattern. A needle experiment disclosed that the inner echogenic and the hypoechoic lines were displayed in front of the true water-tissue interface, which was represented by the outer echogenic line. The authors conclude that the double-line pattern is thus an artifact.

Aorta↗
PubMed1990

Histopathology of microarterial anastomoses: end-to-end versus end-in-end (sleeve) technique.

The healing process of microarterial anastomoses after two different techniques is described after an evaluation of 80 rabbit arterial anastomoses. The two techniques used were as follows: group I, conventional end-to-end technique; and group II, end-in-end (sleeve) technique. After operation the anastomoses were checked at 1 hour, 24 hours, 3 days, 7 days, 2 weeks, 6 weeks, 3 months, and 6 months. The changes occurring at the tunica intima, tunica media, and adventitia were histologically evaluated and morphometric measurements were taken at the anastomotic site. Histologic evaluation of both techniques showed that the rabbits treated with the sleeve technique healed faster with less endothelial damage. The sleeve technique presented a different healing pattern but comparable long-term patency rates with the conventional end-to-end anastomosis technique.

Anastomosis, Surgical↗
PubMed1986

[Histological study on the arterial wall of Göttingen miniature swine].

In order to clarify the histological aspects of arterial walls of miniature swine, 41 arterial segments removed from each of 17 Göttingen miniature swines/csk at 6-12 months after birth were examined by light microscopy. Every segment was classified into three types--elastic, transitional, and muscular--according to its histological architecture. Each type was identified on the basis of relative volume and disposition of elastic tissues, collagenous fibers, and smooth muscles in three coats, Tunica intima, Tunica media, Tunica externa. The distribution of each type was demonstrated in a transition from the elastic to the muscular type. The transitional type was designated as a representative type of artery in transitional regions between elastic and muscular types and had some characteristic structures like a mixture of both of them. This type also had longer regions in the back district with the heart as the starting point, such as the Aorta abdominalis, than that of the front. Every artery belonging to the three types had some different structures at different levels, respectively. It was supposed that the histological arrangement of tissues in the walls of a vessel from various parts of the arterial tree would respond properly to the functional demand.

Animals↗
PubMed1998

Systemic atherosclerosis in dogs: histopathological and immunohistochemical studies of atherosclerotic lesions.

Histopathological and immunohistochemical studies were carried out on five cases of canine systemic atherosclerosis. The five animals were male, and showed hypercholesterolaemia and hypertriglyceridaemia on biochemical analysis of plasma. Histopathologically, atherosclerotic lesions were seen in the aorta and muscular arteries in many organs, including the heart, spleen, kidneys, lungs, pancreas, alimentary tract, urogenital organs, eyes, prostate and urinary bladder. The lesions were characterized by the deposition of lipids and infiltration of lipid-laden foamy cells in the tunica intima and tunica media, sometimes forming fibrofatty plaques, containing abundant sudanophilic material, cholesterol clefts and mineralized material. The lesions started in the tunica intima and extended to the tunica media and tunica adventitia. Immunohistochemical examination with canine apolipoprotein B-100 (CApoB-100) antibody identified the lipids containing low density lipoprotein. Immunoreactivity to CApoB-100 antibody was recognized in the tunica intima, lipid-laden foamy cell cytoplasm and smooth muscle cells in the tunica media, and fibrofatty plaque. These histopathological and immunohistochemical features were similar to those of human atherosclerotic lesions.

Age Factors↗
PubMed1987

Diabetic macroangiopathy. Quantitative histopathological studies of the extramural coronary arteries from type 2 (non-insulin-dependent) diabetic patients.

A morphometric study was performed on histological sections of the extramural coronary arteries from 10 Type 2 (non-insulin-dependent) diabetic patients and 10 non-diabetic subjects, matched for age and sex. Standardised samples were taken from the two coronary arteries and the fractional contents of Periodic Acid-Schiff-positive material, acid mucopolysaccharides and connective tissue was determined in the arterial tunica media from the two groups using a point-counting technique. The thickness of tunica intima and tunica media was obtained by micrometric measurements. There was no difference in the thickness of tunica intima with and without atherosclerotic plaque between the vessels from diabetic and nondiabetic hearts. However, the thickness of tunica media was significantly reduced in arteries from the diabetic patients (2p less than 0.01). In tunica media of the diabetic patients there was a significant increase (50%) in the amount of Periodic Acid-Schiff-positive material (2p less than 0.01), whereas the content of acid mucopolysaccharides (alcian-blue positive) was significantly reduced (2p less than 0.02). These changes in tunica media were similar in areas below and outside the intimal atherosclerotic plaques. The content of connective tissue was found to be significantly increased in the arteries from the diabetic patients, but only in areas outside atherosclerotic plaques (2p less than 0.025). There was no correlation between the observed changes in tunica media and the known duration of diabetes. The results obtained in the present study may be ascribed to the presence of a non-atherosclerotic diabetic macroangiopathy.

Aged↗
PubMed1992

Immunohistochemical studies on the distribution of cellular myosin II isoforms in brain and aorta.

The distribution of nonmuscle myosin isoforms in brain and aorta was studied by using polyclonal antibodies against two synthetic peptides selected from a region near the carboxyl terminus of bovine brain (peptide IIB) and human macrophage (peptide IIA) myosin. Immunoblots of brain homogenates and purified myosin showed two major bands stained by anti-peptide IIB (MIIB1 and MIIB2) and a minor band stained by anti-peptide IIA (MIIA2). Polyclonal anti-human platelet myosin antibodies did not react with MIIB isoforms. In cryosections from bovine, rat, and mouse brains, anti-peptide IIB stained most neuronal cells. In bovine cryosections, glial staining was also observed. In contrast, anti-peptide IIA and anti-platelet myosin antibodies primarily stained blood vessels. In bovine aorta, the anti-peptide antibodies recognized four bands, MIIB3, MIIB4, MIIA1, and MIIA2. Only MIIA2 was recognized by anti-human platelet myosin antibodies. In bovine aorta cryosections, anti-peptide IIB stained smooth muscle cells in tunica intima and tunica media but did not stain endothelial cells. Anti-peptide IIA stained smooth muscle cells in the tunica media, and endothelial cells of vaso vasorum but not of aorta. Only polyclonal anti-platelet myosin antibodies stained the endothelial cells of aorta tunica intima. These results indicate that multiple isoforms of cellular myosins exist in mammals, that these isoforms are expressed in a cell specific manner, and that the major myosin isoforms isolated from whole brain originate from neurons and, at least in bovine brain, from glia, but not from blood vessels.

Amino Acid Sequence↗