Changes in the walls of autologous venous grafts after transplantation into arteries

In 54 dogs 76 operations on plastics of the common carotid arteries with the femoral vein segments have been performed. The animals have been observed for 3 days--1.5 years. The grafts, preserving their permeability, have been studied using a complex of anatomical, histological and micromorphometric techniques. At early stages after the operation (up to 7 days), dystrophic and necrobiotic changes predominate in the wall of the venous graft. As a result of overstretching of the denervated and devascularized vessel, under the effect of a high arterial pressure, nearly total rejection of the endothelial lining takes place, as well as death of some smooth myocytes in the middle tunic; this determines appearance of early thromboses. During 2-6 months after the operation, against the background of a good revascularization of the graft, restorative and adaptive changes develop in its wall. The intima becomes thick at the expense of formation of the obliquely situating layer of myocytes, as well as the result of parietal thromboses organizing on the deendothelized internal surface. These thickenings are especially well seen in the zones of anastomoses. In 6 months--1.5 years after the transplantation into the artery, as a result of constriction of the vessels feeding the graft and reduction of blood stream along them, atrophic and sclerotic changes increase in the wall. The intimal thickenings often acquire the pattern of fibrous patches, that make the lumen more narrow; this can cause appearance of late occlusions and thromboses of the grafts.     

Structural features of the intrinsic venous bed of the human urinary bladder

The intraorganic veins of the human urinary bladder have been studied in a vast sectional material. The veins within the organ make an enormous multilayered plexus which is differently organized in various layers of its wall. Abundant anastomoses, multiplicated ways for outflow from every layer, manifested interactions between the venous plexuses are specific for the intraorganic venous bed of the urinary bladder. The structures for an active regulating the hemomicrocirculatory blood stream are widely presented in the urinary bladder. In its every tunic certain specific morpho-functional features for organization and adaptation of the intraorganic venous bed are revealed.     

Theoretical study on flow-dependent concentration polarization of low density lipoproteins at the luminal surface of a straight artery

It is suspected that physical and fluid mechanical factors play important roles in the localization of atherosclerotic lesions and intimal hyperplasia in man by affecting the transport of cholesterol in flowing blood to arterial walls. Hence, we have studied theoretically the effects of various physical and fluid mechanical factors such as wall shear rate, diffusivity of low density lipoproteins (LDL), and filtration velocity of water at the vessel wall on surface concentration of LDL at an arterial wall by means of a computer simulation of convective and diffusive transport of LDL in flowing blood to the wall of a straight artery under conditions of a steady flow. It was found that under normal physiologic conditions prevailing in the human arterial system, due to the presence of a filtration flow of water at the vessel wall, flow-dependent concentration polarization (accumulation or depletion) of LDL occurs at a blood/endothelium boundary. The surface concentration of LDL at an arterial wall takes higher values than that in the bulk flow in that vessel, and it is affected by three major factors, that is, wall shear rate, gamma w, filtration velocity of water at the vessel wall, Vw, and the distance from the entrance of the artery, L. It increases with increasing Vw and L, and decreasing gamma w hence the flow rate. Thus, under certain circumstances, the surface concentration of LDL could rise locally to a value which is several times higher than that in the bulk flow, or drop locally to a value even lower than a critical concentration for the maintenance of normal functions and survival of cells forming the vessel wall. These results suggest the possibility that all the vascular phenomena such as the localization of atherosclerotic lesions and intimal hyperplasia, formation of cerebral aneurysms, and adaptive changes of lumen diameter and wall structure of arteries and veins to certain changes in hemodynamic conditions in the circulation are governed by this flow-dependent concentration polarization of LDL which carry cholesterol.     

Age-related dynamics of blood supply and vascular-tissue interrelations in the human pineal body

Thirty-seven pineal bodies have been studied. They have been obtained from persons of both sex at the age of 18 up to 88 years, perished from accidental causes. Specific volumes of the epiphyseal tissues and vascular constructions of all types have been determined in histological preparations. In young age (up to 40-45 years) the volume of the intraorganic epiphyseal vascular bed is greater, and its blood supply is better than in persons of elderly and old age, when the sclerosing process in the organ occurs at the expense of outgrowth of fibrous elements of the connective tissue carcass. During the pineal body involution, the volume of its intraorganic vascular bed decreases essentially. This results in certain disturbances of blood supply and affects functional activity of the organ.     

Blood vessels of the epiphysis in comparative-anatomical aspect]

The structure of the epiphysis and its inner blood vessels were studied in the representatives of nine orders of placental mammals and in man by means of injection of stained masses into the arteries and veins and subsequent preparation of histological sections. Not only form and topography of the organ differ in the representatives of different orders, but histological picture of the epiphysis is specific for each of them. In insectivores and chiroptera the loops of the inner three-dimensional capillary network are stretched along the longitudinal axis of the organ. In the epiphysis of carnivores, ungulata and monkey, the intraorganic vessels are situated in stromal trabeculae and the loops of the capillary network have polygonal shape. The intraepiphyseal vessels in man are arranged in peculiar baskets which envelope parenchymal lobules. The intraorganic veins beginning from the loops of the capillary network do not follow the arteries penetrating into the organ, but independently go to different surface parts of the organ where they flow into extraorganic veins.     

Wall stress of the cervical carotid artery in patients with carotid dissection: a case-control study

Spontaneous internal carotid artery (ICA) dissection (sICAD) results from an intimal tear located around the distal carotid sinus. The mechanisms causing the tear are unknown. This case-control study tested the hypotheses that head movements increase the wall stress in the cervical ICA and that the stress increase is greater in patients with sICAD than in controls. Five patients with unilateral, recanalized, left sICAD and five matched controls were investigated before and after maximal head rotation to the left and neck hyperextension after 45° head rotation to the left. The anatomy of the extracranial carotid arteries was assessed by magnetic resonance imaging and used to create finite element models of the right ICA. Wall stress increased after head movements. Increases above the 80th and 90th percentile were located at the intimal side of the artery wall from 7.4 mm below to 10 mm above the cranial edge of the carotid sinus, i.e., at the same location as histologically confirmed tears in patients with sICAD. Wall stress increase did not differ between patients and controls. The present findings suggest that wall stress increases at the intimal side of the artery wall surrounding the distal edge of the carotid bulb after head movements may be important for the development of carotid dissection. The lack of wall stress difference between the two groups indicates that the carotid arteries of patients with carotid dissection have either distinct functional or anatomical properties or endured unusually heavy wall stresses to initiate dissection.     

Age-related characteristics of the organic angioarchitectonics of normal rats and in arterial hypertension

Architectonics of intraorganic arterial vessels in the cervical cortex, heart, kidneys and spleen have been investigated in 40 normotensive and spontaneously hypertensive rats, 6 months and 1 year old. In all the organs studied a direct dependence has been revealed between the degree of changes in the intraorganic arteries and relative content of the arterial vessels in the tissue organs. Functional changes of the arterial vessels in the organs studied observed during the hypertensive phase, transfer into the organic ones, as a result of prolonged adaptation, when the stage of a stable hypertension takes place.     

Condition of the internal arterial and microcirculatory bed of the neck muscles of the dog after simultaneous ligation of the common carotid and vertebral arteries

In 21 mongrel dogs changes in the intraorganic arterial and microcirculatory bed of the cervical muscles have been studied after a simultaneous ligation of the common carotid and vertebral arteries. The most pronounced changes of rearrangement are observed during early periods after the operation (up to two months). The form, size of the arterial loops and direction of the blood stream change in them. On the base of the arterio-arterial anastomoses collateralies are formed, their degree of development is progressing with the increase of the postoperative time. The arteriolo-arteriolar anastomoses in small loops convert into microvascular collateralies that are of importance only during early postoperative stages. The new conditions of hemodynamics at the arteriolar level result in a dependent rearrangement in other links of the microcirculatory bed, where a number of compensatory-adaptive mechanisms are revealed. After the magistral by-pass ways are completely formed, the changes observed disappear and the microcirculatory network acquires the features specific for intact animals.     

The role of the pericytes of the adventitial microcirculation in the arterial intimal thickening

Segments of rat femoral arteries, with one collateral each, occluded between ligatures and dissected from surrounding tissue, developed intimal thickening, with or without ligation of their collaterals. Numerous newly-formed capillaries from the surrounding arterial microcirculation growing into the adventitia, tunica media and intimal thickening were demonstrated by means of serial longitudinal sections, predominantly in the ostium of the collateral. When the ligatures were applied without damaging the microcirculation surrounding the artery and the normal continuity of the adventitial vessels was unchanged, earlier presence of intimal thickening was observed. When the fibrous layers of the adventitia were removed at the moment of the arterial ligation, the continuity between newly-formed vessels of the neoadventitia and those growing into the media and neointima was much more evident. It was then noted that the pericytes constituted a major component of the intimal thickening. The introduction of contrast material in microcirculation confirmed the connections between newly-formed adventitial and intimal vessels. At the beginning of the experiment, autoradiographic studies showed an increased DNA synthesis in the cells of preformed postcapillary venules and capillaries of surrounding arterial microcirculation and later in those of the newly-formed vessels growing into the arterial wall. These results indicate that newly-formed capillaries derived from surrounding arterial microcirculation penetrate the wall of the occluded arterial segments and contribute to the intimal thickening formation. It is likely that the pericytes and endothelial cells (EC) of these ingrowing vessels are sources of myointimal cells at the intimal thickening and of endothelium at the luminal surface, respectively.     

Ultrastructure of the cyst wall of sarcocysts of the roe deer (Capreolus capreolus L.) (author's transl)]

The ultrastructure of the cyst wall of two types of sarcocysts from roe deer is described. In the thin-walled cyst (wall thickness 0.18-00.26 micrometer), the primary cyst wall forms long, finger-shaped protrusions distant from one another and running in parallel with the surface of the cyst (Figs. 1a--d, FP). No fibrils are observable in the protrusions. The primary cyst wall between them forms numerous bubble-like invaginations (Fig. 1c, arrows). In the thick-walled cysts (wall thickness 4.9--7.49 micrometer), the primary cyst wall forms massive, palisade-like protrusions lying close one to another (Figs. 2a, c). There are numerous fibrillar and tubular structures in these protrusions (Fig. 2d), and the primary cyst wall occasionally forms shallow invaginations at the base of some protrusions (Fig. 2b). The unit membrane onthe surface of some protrusions is slightly undulated and covered with a layer of short and thick bars on the outside. The sarcocysts found in roe deer are compared with those from cattle and sheep.     

Trophoblastic invasion and the development of uteroplacental arteries in the macaque: immunohistochemical localization of cytokeratins,desmin, type IV collagen,laminin, and fibronectin

The processes by which trophoblast cells invade and modify the walls of the uteroplacental arteries of macaques during the course of gestation were examined. Antibodies to cytokeratins were employed to identify trophoblast, anti-desmin antibody to identify smooth muscle, and antibodies to type IV collagen, laminin, and fibronectin to examine changes in extracellular matrix distribution in the arterial wall. During early gestation, endovascular trophoblast adhered to the arterial wall, often in an asymmetrical distribution. As trophoblast cells moved outwardly into the tunica media, the basement membrane underlying the endothelium was lost, as indicated by gaps in the layer when stained for type IV collagen and laminin. Trophoblast cells became sequestered in the vessel wall where they hypertrophied and became surrounded by a capsule containing type IV collagen and laminin. As the trophoblast cells became established in the vessel wall, the muscular layer of the artery became discontinuous. Throughout gestation it was common for trophoblast cells to invade the vessel intimal layer and share the lining of the artery with typical endothelial cells. This general disposition of endovascular and intramural trophoblast persisted into late gestation. In addition, and contrary to the results of earlier studies of macaques, we identified trophoblastic invasion and modification of myometrial segments of the uteroplacental arteries in later gestation. We also found evidence of interstitial trophoblast cells among the stromal cells of the endometrium, especially during early gestation.     

V-shaped cushion at the origin of bovine pulmonary supernumerary arteries: structure and putative function.

This study investigates the anatomic structure at the origin of pulmonary supernumerary arteries and their parent conventional artery. Histological examination showed that at the origin of each supernumerary artery the wall of the parent conventional artery is organized into a distinct V-shaped structure, which begins on the hilum side of each supernumerary artery as a funnel-shaped channel running into the supernumerary artery. The base of the channel is particularly thin walled. The lateral walls of the channel are composed of musculoelastic cushions that become more pronounced toward the supernumerary artery and fuse on its distal side, forming a baffle that projects over the supernumerary artery lumen. These V-shaped structures/cushions were observed with video stereo dissecting microscopy in both an open and closed state in isolated arteries in vitro. Pulmonary vasoconstriction of isolated arteries with the thromboxane A(2) mimetic U-46619 increased the number of V-shaped structures in the closed state. These studies indicate the presence of a novel anatomic structure at the origin of pulmonary supernumerary arteries, which may be able to regulate blood flow into the supernumerary artery.     

Ultrastructural characteristics of elastogenesis in the major arteries of the canine hindlimb during leg lengthening

In mature dogs ultrastructural peculiarities of elastogenesis in femoral and anterior tibial arteries have been studied at various stages of the bone elongation after Ilizarov method. From the end of the 1st week of distraction, metabolic activation of intimal smooth muscle cells is revealed, from the 2d week--in the middle tunic, and on the 5th-6th week--fibroblasts of adventitia of the arteries investigated, directed to biosynthesis of intracellular predecessors of elastin and microfibrils of the elastic fibers. This results in activation of elastogenic processes, elastic structures in all three tunics of the arteries are observed to newly form and rearrange. The factor that stimulates and maintains elastogenesis is strain of extension, that occurs in the vessels during the experiment. Elastogenesis in the major arteries, when the extremity is elongated, has much in common with development of elastic components in the vascular wall in animals during the process of physiological growth.     

Age-related characteristics of the stromal-parenchymal relations of the human thymus

In 155 thymuses and in 57 capsules of the organ, distributed according to 12 age groups, beginning from fetuses of 5 months up to 90 years, age transformations of stromal-parenchymatous relations of the human thymus have been studied and quantitatively estimated. During the postnatal ontogenesis the thymic capsule and its intraorganic connective, tissue frame together with the parenchyma undergo certain phase reorganizations, specific for each age period. The greatest development of the thymic connective tissue frame reaches at the age of 1-3 years and during sex maturation period. The thymic lymphoepithelial tissue exists during all age periods. In the thymic adipose body foci of extramedullary lymphopoesis are revealed, beginning from the first mature up to the elderly age.     

Ultrastructure of sperm cells in the female gonoduct of Xiphinema

The ultrastructure of the sperm cells in the female gonoduct of the nematodes Xiphinema theresiae and X. pinoides is described. The nucleus of the sperm cells is composed of several electron-dense clumps of chromatin that is not surrounded by a nuclear envelope. A layer of mitochondria, in which the mitochondrial cristae are only rarely visible, lies around the nuclear material. In the surrounding cytoplasm packets of electron-dense fibres are abundant. The sperm in the uterus have the following surface differentiations: highly intertwined protrusions between adjacent sperm cells, protrusions coinciding with the plication of the inner uterine wall and a slightly undulated surface towards the uterine lumen. It is argued that in the uterus, the sperm cells actively move in proximal direction by a mechanism resembling pseudopodial movement, in which the packets of fibres are involved. In the oviduct, the sperm cells loose their surface protrusions and the packets of fibres gradually become less abundant. Since the oviduct has no pre-formed lumen, the sperm cells appear to wedge their way along by forcing oviduct cells apart.     

Viability of the kidney following autovenoplasty of its artery]

A segment of one of the renal arteries of the dog was substituted for a piece of the femoral vein of the same dog. Along the site of vascular anastomoses the kidney was excluded from general blood circulation. The results of the vessel plastics were not always favourable. Inspite of the independence of anastomoses in the course of operation, the lumen of the substituted piece of the renal artery underwent deformity in a number of experiments, the circulation of the kidney was disturbed, the parenchyma of the organ was injured, a part of renal bodies and tubules were atrophied, intraorganic vessels, especially glomeruli were reconstructed. The alterations were of focal character. In general the structure of the kidney was preserved. In most experiments the substitution of the renal artery for the own vein did not cause any disorders. The wall of the transplanted vein was soon reconstructed--artealized, the renal parenchyma kept normal structure. The success of vascular plastics and the full value of blood circulation was controlled by removing the twin organ. Animals with one kidney lived practically unlimited time without obvious disorders, the content of nitrogen in the blood was normal, no alterations were found in intraorganic vessels and the renal parenchyma.     

Early calcification patterns of the iliac arteries and their relation to the arterial structure

Summary Gross calcifications of the common iliac and internal iliac arteries represent a common finding in newborn children and infants. In both arteries, the calcific deposits regularly appear in certain areas of the arterial luminal surface only, whereas the other parts of the arterial wall remain free of gross lesions even in cases with a pronounced calcification. In the common iliac artery, the lateral wall of the vessel and the adjacent sectors of the anterior and posterior wall represent the predilection site of calcific deposits. In the internal iliac artery, the gross calcifications have been regularly demonstrated in the dorso-medial wall. The predominant localisation of the calcification in these parts of the vessels and its absence in the others depend on the definite structural features of the arterial tube and different affinity for calcium of the individual structural elements. In both iliac arteries, only the primary internal elastic membrane undergoes early calcification. However, unlike the most muscular arteries, this membrane is not developed in the whole arterial circumference of the common iliac and internal iliac arteries, but is absent in large areas of their arterial luminal layer. In these areas, the subendothelial or subintimal elastic layers are formed by the networks of longitudinally arranged elastic fibers or membraneous elastic structures which arise from the elastic networks with the further growth. These elastic elements always stay free of calcific deposits. The structural features found in both iliac arteries may be important for the development of the later pathological changes.     

A numerical simulation of intimal thickening under shear in arteries.

A model of intima thickening proposed by Friedman and his coworkers (1,2) is incorporated in our computer code to simulate the growth of intima under shear. The computer code is based on a finite volume method in a boundary-fitted coordinate system. It is found that the model yields an evenly-distributed thickening over a straight, smooth vessel wall. However, in a stenosed or a curved artery, thicker intima can be formed in preferential regions due to unevenly-distributed wall shear stresses. The results clearly demonstrate the correlations among the geometry, wall shear rate and the plaque localization in arteries. The model is applied to a straight artery with a stenosis or sinus, a smooth curved artery and a stenosed curved artery. The effects of stenosis/sinus and lumen curvature on the flows and the intimal thickening are studied. The simulation provides a numerical visualization of the intimal thickening in a dynamic way.     

Intraorganic venous bed of the stomach cardia in children during the first 3 years of life

The intraorganic venous bed of the gastric cardial part has been studied in 27 organs, obtained from children corpses of both sex beginning from birth up to three years of life. They died from causes that were not connected with gastric or vascular system pathology. The results of the investigation prove the presence of mucous, submucous, muscular and serous-subserous venous plexuses in the wall of the gastric cardial part in children of the first three years of life. Every membrane of the stomach wall has its specific structure of the venous link in the microcirculatory bed. In the stomach mucous membrane already in a newborn there are complexly built microcirculatory pathways. Age changes are mostly expressed in the venous link of the gastric mucous membrane; this is probably connected with functional activity of the given layer of the organ. The largest venous vessels are situated in the gastric submucous base. By the end of the newborn period and, especially fully, during the successive age periods immune protection of the gastric wall is formed as an accumulation of lymphoid tissue to an antigenic effect of food. In these age groups certain structural mechanisms of blood outflow from the gastric wall appear.     

Endothelial cell protrusions in the rat aortic wall. Immunocytochemical evidence for an alternative transendothelial passage of plasma proteins.

Focal morphological changes in the endothelial lining were observed in the aortic wall of control rats. They consisted of endothelial cytoplasmic projections and vacuolar structures protruding towards the luminal space and containing electron-dense material. Some of these structures were observed to open into the subendothelial space. Endogenous albumin was detected in these compartments by applying protein A-gold immunocytochemistry to thin tissue sections of glutaraldehyde-fixed, Lowicryl-embedded aortic segments. The labelling was mainly distributed along the plasma membrane of the projections as well as over the dense content of the endothelial protrusions. The presence of endogenous albumin in these endothelial structures, together with their opening into the subendothelial space, suggests a role for these structures in an alternative transendothelial transport of albumin.