Enzymatic differentiation of arterial and venous segments of the capillary bed during the development of free muscle grafts in the rat

The revascularization of freely grafted muscles in the rat was studied by histochemical reactions that on frozen sections stain the arterial part of the capillary bed blue (alkaline phosphatase [AP] reaction) and the venous part of the capillary bed red (dipeptidyl peptidase IV [DPP IV] reaction). In 112 rats the extensor digitorum longus or soleus muscles were freely grafted and removed at various times up to 93 days following the surgery. In cross section, the capillaries of a normal muscle show a mosaic pattern of staining for the activity of the two enzymes. After grafting, DPP IV activity of capillaries is lost throughout the entire graft within a day or two; but within ischemic muscle, weak and diffuse AP staining persists in capillary remnants for up to 6 days. In the very periphery of the graft AP staining is also preserved in partially damaged capillaries. By 4 days, new AP-positive capillaries can be identified at the periphery of the graft, and in succeeding days AP-positive capillaries are found progressively nearer the center of the graft. At 7 days, the capillary/muscle-fiber ratios are 66% of normal in the periphery of the graft and 44% in the intermediate zone. DPP IV-stained capillaries are not seen until 7 days after grafting. By 60 days, when the grafts have become stabilized, the mosaic pattern of capillary staining has become reestablished. In mature grafts, the number of capillaries per unit area was slightly higher than that in control muscles, but the capillary/muscle-fiber ratio was slightly lower, owing to the smaller than normal cross-sectional areas of the regenerated muscle fibers.     

Structural and functional characteristics of myocardial capillaries after resection of the lungs

In the experiment performed on 107 dogs, after resection of 33-75% of the pulmonary volume, it has been stated that considerable disturbances take place in the myocardial microcirculatory bed. At early stage after the operation the amount of capillaries per 1 mm2 of the section increases, their lumens become wide. With elapse of time after the operation, as a result of myocardial hypertrophy, density in arrangement of the capillaries decreases, and the transversal section area of the cardiomyocyte per one capillary increases. In the capillary walls destructive changes are also noted; they result in myocardiodistrophy and in development of cardiac failure.     

Morphofunctional characteristics of microcirculation in the skin of girls 5-17 years of age

In 261 girls year-to-year morphofunctional transformations of spatial composition of the skin microcirculatory bed have been studied at rest and after a dynamic local load. By means of biomicroscopy main regularities in development of the skin capillary network have been revealed in the nail torus in the postnatal ontogenesis. Formation of the microvessels reactivity during various age periods and maturation of mechanisms of the compensatory-adaptive reactions are connected with formation of the definitive composition of the microcirculatory bed, that in girls corresponds to 11-12 years. Qualitative transformations in the skin capillary network bring certain quantitative changes in the structural microcirculatory parameters--increasing diameter of microvessels and increasing density of functioning capillaries.     

Changes in the capillary bed of the skeletal muscles in various periods following nerve section]

The authors studied the changes in the capillary bed of the gastrocnemius in rats at various periods after the section of the sciatic nerve. There was revealed a significant reduction of the total number of capillaries and of the number of functioning capillarites at the period of denervation and their increase during the reinnervation.     

Function and reactivity of the microvascular bed in human neuroses

By contact microscopy the state and reactivity of the capillary bed (capillaries of the cheek mucosa) were studied in neurotic patients with different levels of arterial pressure (AP). It has been shown that at constant AP capillariscopic parameters (diameter, length and number of capillaries in the visual field) are relatively stable. Neuroses with hypertension are characterized by uneven (more expressed in arterioles) contraction of the capillaries, accelerated development and greater duration of reactions to the mental stress and applications of adrenaline and noradrenaline solutions in comparison with healthy persons. In hypotension, uniform capillaries contraction and slower development of the above reactions are observed.     

Morphofunctional adjustments in the microvasculature of the conjunctiva of the human eye at different stages of the postnatal period of ontogenesis

By means of the biomicroscopy method under vital conditions, conjunctival microvessels in the eyeball have been investigated in 240 healthy boys 7-17 years of age at the state of rest and at the antiorthostatic action. The rearrangement of the conjunctival microcirculatory bed of the eyeball completes on the whole by 13-14 years of age and is characterized by transition from diffuse to a more refulate structure (the number of the main magistrals lessens, they become larger, the number of capillaries functioning simultaneously decreases, the role of the shunting blood stream becomes more important). With this process in ontogenesis, certain changes in reactivity of microvessels are connected. The quickest and the most adequate responses of the microvessels appear in the development by the time when the definitive composition of the conjunctival microcirculatory bed in the eyeball is formed. Since that time the microcirculatory system reaches its optimal level of functioning and all the processes are performed in the most economic regimen.     

Method of complex morphofunctional study of the capillary bed of the thyroid gland]

The method is based on the cytospectrophotometric estimation of the histochemical reaction to alkaline phosphatase in the gland capillary and on determination of the relative volume occupied by the functioning capillaries. A model experiment under conditions of hyperplasia and hypoplasia of the organ has shown considerable differences in the gland blood supply. Under these conditions the changes of the functioning capillary bed were more pronounced than those of the organ mass.     

Effect of chronic alcoholism on the state of the microcirculatory bed of the myocardium

Ultrastructure of myocardial capillaries of rats was studied in cases of chronic alcohol intoxication, experimental alcoholic cardiomyopathy (ACM) and its correction with antioxidants (vitamin E, dibunol). Alterations in the microcirculatory bed were similar in all groups of animals irrespective of disturbances in cardiomyocytes. Cardiomyocyte ultrastructure was improved after treatment with antioxidants, but capillary bed was the same as in untreated animals. High dibunol doses caused the onset of perivascular sclerosis. Disturbances in the microcirculatory bed are, probably, the first step in the determination of ACM pathogenesis and therapy of ACM must be directed at the correction of both alterations of cardiomyocytes and capillary bed.     

The microcirculatory bed of the normal rat uterus and in exposure to laser radiation

By means of scanning electron microscopy of corrosive casts angioarchitectonics of mucous and muscular membranes of the white rat uterus has been studied at diestrus phase, normal and under influence of laser irradiation with exposition of 1 min and 1 h. The morphometric investigation performed has proved presence of local peculiarities in organization of the uterine capillary bed. After irradiation for 1 min a noticeable increase in transversal diameter and capillary density is observed, numerous protrusions appear on their walls. When irradiation lasts for 1 h a relative loose of the uterine capillary network is observed, which is especially manifested in endometrium: capillaries demonstrate an increased convolution and decreased diameter.     

State of the capillary network of rat myocardium in the presence of hypertrophy and physical loading

Morphofunctional state of the capillary network in various myocardial parts was studied in white rats under normal conditions, myocardial hypertrophy of different degree and under physical loading. It was demonstrated that density, metabolic surface and capacity of the capillary bed is larger in the right ventricle than in the left one. The capillary blood supply in hypertrophied myocardium, increasing simultaneously with hypertrophy, at the state of rest corresponds to its increasing mass. On the contrary, under maximal physical loading functioning of the capillary part in the myocardium becomes unadequate that is evident from a decreasing activity of the test animals.     

Reorganization of the lymphomicrocirculatory bed of human myocardium in ontogenesis

By means of Gerota mass and silver nitrate solution, injected into the myocardium and its vessels, as well as using the scanning electron microscopy technique for corrosive casts, links of the human myocardial lymphomicrocirculatory bed have been studied, beginning from 6-9-month-old fetuses up to elderly and old age persons. Changes in form, dimensions and amount per a volumetric unit have been stated in myocardial capillaries and postcapillaries. These signs demonstrate that the myocardial lymphatic system has different importance for each stage of individual development of the human heart.     

Myocardial capillaries in the fetal and the neonatal rat: a morphometric analysis of the maturing myocardial capillary bed

Developing myocardial capillaries from 16-day-gestation fetus to adult undergo several morphological changes including a thinning of the lateral extensions of the capillary endothelial cells, the formation of a basal lamina, and an increase in the number of plasmalemmal vesicles. A decrease in the extracellular space, an increase in the number of capillaries, and a decrease in the capillary diameter were also observed during the developmental period. In view of these ultrastructural changes, a morphometric analysis was made on the developing myocardial wall to demonstrate specific quantitative changes. The volumes which were occupied by capillary endothelial cells, capillary lumina, extracellular space, and myocardial myocytes within a reference volume of myocardium were measured; and we found that 8% of the reference myocardial volume was occupied by capillary endothelial cells, 85% was occupied by myocardial myocytes, 4% was occupied by capillary lumina, and, except for a significant change in extracellular space at 16 days gestation, 3% was occupied by extracellular space. Each volume ratio was found to be nearly constant throughout the studied period. In contrast to this constancy in the volume ratios, other parameters which were measured demonstrated significant changes during the developmental period studied. These overall changes include a 135% increase in capillary density, a 63% increase in luminal surface area of capillary endothelial cells, a 24% decrease in capillary diameter, a 12% decrease in diffusion distance, and a 35% decrease in the diameter of the erythrocyte population.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in the respiratory muscles and their microcirculatory bed during exposure of the body to chronic hypoxia and its aftereffects

Changes of the respiratory muscles have been studied under the effect of a rarefied atmosphere when the pressure is 560 mm Hg (2,500 m), 405 mm Hg (5,000 m), 286 mm Hg (7,500 m) and during the period of their aftereffect. The experimental group consists of 260 and the control group--of 130 white rats. Adaptation of the respiratory muscles to the effect of the rarefied atmosphere at the pressure of 560 mm Hg takes place mainly at the expense of certain functional changes of the microcirculatory bed and hypertrophy of the muscle fibers. The period of aftereffect is characterized with normalization of these phenomena. Adaptation of the respiratory muscles at the pressure of 405 mm Hg takes place at the expense of hypertrophy of the muscle fibers, small destructive changes and a complex rearrangement of the microcirulatory bed. During the period of aftereffect, by the 40th day no destructive changes are noted in the muscle tissue. The capillary bed undergoes some rearrangements by the 42d -56th day with increasing quantitative indices per area unit. This results in improvement of the muscles nutrition. In the respiratory muscles at the pressure 286 mm Hg, atrophic changes in the muscle fibers take place at certain stages of the experiment. Essential destructive changes are observed, rearrangement of the microcirculatory bed with decreasing convolution of the longitudinal capillaries and a decreasing number of the transversal capillaries are noted by the end of the experiment. During the period of aftereffect, by the 56th day, the external and internal intercostal muscles completely restore their structure, and in the diaphragm the destructive changes remain. By the same time, the microcirculatory bed becomes more rare at the expense of decreasing capillarization of the muscle fibers and a decreasing number of the transversal capillaries.     

Changes in the parameters of skin capillaries during the adaptation of students from the countries of Asia, Africa and Latin America

Time-dependent changes in diameters of various parts of the capillaries, distances between loops of the skin papillary capillaries in the nail wall and number of functioning capillaries per 1 mm2 of the skin surface have been studied biomicroscopically in foreign students, arrived from hot countries, during the process of their adaptation. Reorganization of these skin capillary parameters, actively participating in processes of heat exchange, demonstrate a time-dependent character. Therefore, by means of regressive analysis it is possible to approximate dynamics of the initial data using suitable theoretical models. The dynamics of average meanings of the capillary diameters in the arterial part subordinates to the hyperbolic dependence, changes of other parameters approach the rectilinear regression.     

Formation of structuro-functional units of the microcirculatory bed of muscles in the postnatal period of the ontogenesis of the white rat

By means of biomicroscopy, histological methods and scanning electron microscopy topological relationships between the white rat m. cremaster microvessels and changes of their spatial organization have been studied in the postnatal development beginning from the 3d to the 14th week. In the terminal link of the microcirculatory bed zonal functional complexes of microvessels--myoangions are revealed. They represent rather autonomic and regularly repeating constructions of microvessels, having spatial regularity in respect to muscle fibers. With age the myoangion increases its stretchness from 303 +/- 14 in 3-week-old up to (70 +/- 3) X 10 mcm in 14-week-old animals. Capillary density in the m. cremaster during the development decreases from 354 +/- 12 up to 210 +/- 4 mcm, respectively. Distance between the longitudinal capillaries increases from 16.1 +/- 1.3 up to 31.2 +/- 1.8 mcm. Increase of transversal connections takes place in the capillary network, increasing number of the branching knots; this demonstrates certain complication of the nutritive link of the muscle microcirculatory bed. By the time of sexual maturation (6 weeks) there is a sharp decrease of the inflow and outflow coefficients. Higher meanings of the coefficient (0.70-0.74) are noted before sexual maturation period in comparison to that in mature animals (0.53-0.55).     

Blood vessels of the periodontium of incisors and molars of the lower jaw of the white rat

By means of injective and noninjective methods, the structural organization of the incisor and molar blood bed has been studied in the white rat mandible. For the periodontal blood bed, distinguishing by a pronounced organo-specificity, distribution of arterial and venous vessels between collagenous fiber bundles and a reticular arrangement of the capillaries is peculiar. A definite connection is clearly seen between angioarchitectonics of different segments of the periodontium, its structure and function. Unequal density of the capillary networks in the area of the epithelial dental organ and difference of the periodontal angioarchitectonics with the lingual and labial surfaces of the incisors are noted. The area of the epithelial dental organ, having a peculiar functional importance, is characterized by multiple pathways of blood inflow and outflow, by concentration of structural-functional adaptations which increase expansiveness, capacity and diffusive surface of metabolic microvessels, by a small critical thickness of the tissue layer between neighbouring capillaries.     

Morpho-functional correlations of the structure of bone cells and adjoining bone matrix in the developing bone

By means of scanning and transmissive electron microscopy methods structure of the developing bone has been studied. Interconnection of the cell structure and spatial organization of the adjoining matrix has been demonstrated. On the surface of the growing bone not only forming areas have been revealed, where under osteoblasts at various functional states, osteoid layer is determined, but also areas of resorption and completed osteogenesis. This demonstrates an interrupted character of osteogenesis at modelling. At the same time for the remodelling process presence of erosive lacunae is specific; they are filled with a newly deposited collagenous matrix. Therefore, it is possible to suppose that formation of the bone as an organ during the postnatal development includes in itself both mechanisms supporting its form at outgrowth of the osseous matrix volume (modeling) and its continuous rearrangement and adaptation to real conditions of functioning (remodelling).     

“Seamless” endothelial cells of blood capillaries

Summary The distribution and number of seamless endothelial cells (SE) were studied in various organs and tissues of rats, rabbits and humans (1) by light microscopy after silver impregnation of the endothelial cell boundaries, (2) by electron microscopy, and (3) in three-dimensional reconstructions of duodenal villi and renal glomeruli. Since SE are situated mostly at branching points, the number of SE is roughly correlated to the number of branchings in the capillary system concerned. SE make up about 50% of all endothelial cells in the renal glomerulum and duodenal villi, and about 30% in the cerebral cortex. However, they rarely occur in bradytrophic tissues. SE have been found exclusively in net capillaries (true capillaries). They seem to be absent in most arterio-venous capillaries (capillary parts of thoroughfare channels), in the capillaries of endocrine glands, as well as in the sinusoidal systems of heart muscle, liver, spleen and bone marrow. It is concluded that SE are developed when tube formation is confined to a single endothelial cell. SE are intercalated most frequently in those capillaries that develop lastly in the terminal vascular bed. The seamless segments are canalized by fusion of intraendothelial vacuoles with pre-existing vascular walls. The existence of SE, confirming the dual structural design of capillary systems, may be used as a detector for net capillaries.     

The microcirculatory bed of the normal rat thyroid and during hypokinesia based on scanning electron microscopy data on corrosion preparations

In 12 mature white rats with body mass of 180-230 g, that are kept in tight pencil-cases for 10, 30 and 90 days (3 rats make the control), by means of scanning electron microscopy of corrosive preparations reorganizations of three-dimensional spatial organization of the thyroid microcirculatory bed are studied. In intact animals single-layered network of the perifollicular capillaries consists of widely anastomotic blood microvessels and makes 68 +/- 7% of the follicular surface. At hypokinesia (Hk) lasting for 10 days, the perifollicular capillaries are sharply dilated, the capillary network area makes 74 +/- 4%. A large amount of processes appear on the capillary walls. On the 30th day of Hk unequal distribution of capillaries on the follicular surface is noted, that is heterogeneity in organization of the perifollicular capillary networks is manifested. In 90 days of Hk reduction of the capillaries is recorded, rarefied pericapillary network prevails, twistedness of the capillaries is clearly manifested, their complex branching decreases. The capillary network area makes 54 +/- 3% of the follicular area. A large amount of pin-shaped protrusions of the capillary wall appear.     

Ultrastructural characteristics of the microcirculatory bed of the human adrenal cortex in prenatal ontogenesis

By means of transmissive electron microscopy the adrenals have been studied in 25 human embryos and fetuses at the age of 6-36 weeks. Certain stages have been revealed in formation of the adrenal cortex microcirculatory bed. In 6-7-week-old embryos (period of diffuse protocapillary bed) endothelial structure and mesenchymal cells, surrounding the adrenal anlage, resemble one another. A distinguished feature of the endothelium is regularly revealed desmosomes and large vacuoles, often found in cytoplasm of endotheliocytes. In 8-12-week-old fetuses (period when the organospecific microcirculatory bed is forming) sinusoid capillaries differentiate in the internal zone of the adrenal cortex; in endothelium fenestrae, "hatches", "locks" are revealed, the capillary basal membrane is formed. During subsequent time of the intrauterine development perfection of the microcirculatory pathways in the adrenals takes place, the arteriolar link of the subcapsular layer including. By the time of birth morphofunctional maturity of the microcirculatory bed in the adrenal cortex is noted.