Ultrastructure of the pulmonary trunk wall during the prenatal period of ontogenesis

By means of transmissive electron microscopy stages of morphogenesis have been studied in the pulmonary trunk wall of 12 healthy human embryos and fetuses of 5-24-week-old. There is a close dependence in development of the smooth muscle component of the middle tunic, elastic and collagenous fibers of the pulmonary trunk wall. In the early prenatal morphogenesis of the pulmonary trunk fibrillogenesis develops intensively, overtakes the differentiation time of myocytes from mesenchymal cells, the collagenous fibers appearing earlier than the elastic ones. The structures, that ensure solidity of the vascular wall (collagenous fibers), appear in embryogenesis earlier that those, ensuring its elasticity (ability to reversible deformity).     

Formation of the muscular and neural components of the femoral artery wall of the dog in early postnatal ontogeny (an ultrastructural and histochemical study)

In puppies of various age (newborn, 2-week-old. 1- and 3-month-old) formation of smooth muscle and neural components in the femoral artery wall has been studied electron microscopically and histochemically. As demonstrate the electron microscopic data, the femoral artery wall is mainly formed by birth, nevertheless, structural components of its each tunic are at various stage of maturation and only by the 3d month the differentiation and specialization process of all cellular elements is fully completed. Owing to a combination of techniques used, it has been possible to follow the dynamics in formation of the innervation apparatus of the femoral artery. In the newborn animals the adrenergic apparatus of the femoral artery is presented mainly as thick fibers of a cable type; they form a plexus with loose loops at the periphery of the external tunic. Varicosities are scanty. By the 3d month there is a well developed network of the adrenergic fibers at the border of the middle and external vascular tunics. Some terminals penetrate into the muscular tunic. There is a great number of varicosities in the neural fiber axons. At the border of the middle and external tunics of the vessel, complex neuro-muscular interrelations are forming with an aim to bring functionally closer the main structural components of the wall. In the course of the early postnatal ontogenesis in dogs up to 3 months of age, in the femoral artery wall certain processes take place directed to ensure the neuroregulatory vasomotor properties of the vessel.     

Role of mechanosignaling on pathology of varicose vein

Varicose veins are the most common vascular disease in humans. Veins have valves that help the blood return gradually to the heart without leaking blood. When these valves become weak, blood and fluid collect and pool by pressing against the walls of the veins, causing varicose veins. In the cardiovascular system, mechanical forces are important determinants of vascular homeostasis and pathological processes. Blood vessels are constantly exposed to a variety of hemodynamic forces, including shear stress and environmental strains caused by the blood flow. In varicose veins within the leg, venous blood pressure rises in the vein of the lower extremities due to prolonged standing, creating a peripheral tension in the vessel wall thereby causing mechanical stimulation of endothelial cells and vascular smooth muscle. Studies have shown that long-term increased exposure to vascular wall tension is associated with the overexpression of HIF-1α and HIF-2α and increased levels of MMP-2 and MMP-9, thereby reducing venous contraction and progressive venous dilatation, which is involved in the development of varicose veins. Following the expression of metalloproteinase, the expression of type 1 collagen increases, and the amount of type 3 collagen decreases. Therefore, collagen imbalance will cause the varicose veins to not stretch. Loss of structural proteins (type 3 collagen and elastin) in the vessel wall causes the loss of the biophysical properties of the varicose vein wall. This review article tries to elaborate on the effect of mechanical forces and sensors of these forces on the vascular wall in creating the mechanism of mechanosignaling, as well as the role of the onset of molecular signaling cascades in the pathology of varicose veins.     

Effect of combined exposure to hypokinesia and gravitational stress on the structure of the wall of the renal vein

Renal veins from 25 rabbits were investigated by means of imbedding in paraffin with subsequent hematoxylin--eosin staining, after Van Gieson and with fuchselin after Hart. Prolonged hypokinesia (over 3 weeks) with subsequent single application of gravitational overloading was stated to produce some structural changes in the wall of the renal vein. They are manifested as loosening of the middle vascular sheath with vacuolization of myocytes and outgrowth of its elastic elements. Hypokinesia of longer duration (8 weeks) with subsequent gravitational overloading produces atrophy of smooth muscle tissue in the middle sheath of the venous wall that brings about decreasing in tonus of the wall of the renal vein.     

Collagen of umbilical cord vein and its alterations in pre-eclampsia

The state of the vascular system of the mother and of placenta is known to exert a great influence on intrauterinal development of the fetus. Pre-eclampsia is the most common pathological syndrome connected with pregnancy. Since collagen is one of the main constituents of the vessel wall a comparison was made with collagen content and its molecular polymorphism in umbilical cord veins of newborns from healthy and pre-eclamptic mothers. It was found that umbilical cord veins of newborns from mothers with pre-eclampsia contained 18% less collagen than those of the newborns from normal pregnancies. This decrease was accompanied by a slight decrease of collagen solubility, but all its types (I, II, IV, V and VI) were present. However, the umbilical vein wall of newborns from mothers with pre-eclampsia contained relatively less of type I and more of type III collagen than the normal umbilical cord. These differences may be connected with a disturbance of blood flow in fetus of a woman with pre-eclampsia.     

Development of the paravascular bed of the vessels of the human heart during the prenatal period of ontogenesis

The paravascular bed of the cardiac vessels has been studied in 128 human fetuses at the age of 3-9 lunar months. Anatomical and histological techniques have been used, morphometrical analysis has been carried out. The paravascular bed of the cardiac wall vessels begins to form from the vascular epicardial network and from the paraneural vessels in 5-month-old fetuses. The paravasal longitudinal tracts are the first to form (the venous ones preceed the arterial). During the seventh month the nutritive vessels and the intramural networks of the main cardiac arteries and veins develop. The formation of the paraarterial bed is connected with the vascular diameter and with thickness of the arterial walls. Certain regularities in development of the venous paravascular bed are defined. By the beginning of the 8th month there are all main components of the paravascular bed of the cardiac vessels.     

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.     

Adrenergic neuromuscular junctions in the cerebral arteries of birds

By means of the histochemical and electron microscopical methods, adrenergic innervation of the middle cerebral artery and its branches have been investigated in three sparrows (Passer montanus), blue rock pigeons (Columba livia), hens (Gallus domestica), hazel-grouses (Tetrastes bonasia), large billed crows (Corvus levaillantii), ducks (Anas domestica) and slaty backed gulls (Larus schistisagus). Neuromuscular connections in all the birds investigated have similar organizational features. Some adrenergic effectors are situated 700 nm from the external layer of myocytes in the vascular middle tunic, and they perform the distant transmission. Other effectors are at the distance of 40-80 nm from myocytes, and they are built according to the synaptic type. They produce certain action upon single muscle cells, thus performing local transmission. For the neuromuscular connections of the cerebral vessels in the birds, presence of multiaxonal complexes is specific. Axons of the complex innervate groups of muscle cells and they are at the distance of 50-270 nm from their plasmic membranes. Perhaps, they combine the local and distant means of transmission.     

Architecture and functional aspects of the distal airways of Antarctic seals with different habits,the Weddell Seal (Leptonychotes weddellii) and the Crabeater Seal (Lobodon carcinophagus)

Summary The lung of the deep diving Weddell Seal is characterized by an unusually well developed periacinar dense collagenous connective tissue, and a thick coat of smooth musculature particularly in the distal bronchioli. Both, collagen and smooth musculature appear to be functionally interrelated, the first serving presumably as site of origin or attachment for the latter. The orientation of the bronchiolar smooth muscle cells is complex: there exists a basic pattern of two crisscrossing helical bundles that wind in opposite direction. In addition, longitudinal bundles are frequent both at the inside and the outside of the muscular coat. Furthermore, more or less complete ringshaped bundles occur as well as groups of muscle fibres running radially into the collagenous tissue of the surroundings of a bronchiolus. This complex architecture presumably allows active adjustment to various physiological needs of the Weddell Seal including as extremes both closing and widening of the bronchiolar lumen. Isometric contractions of the smooth musculature may stiffen the wall of the distal airways while diving. In the Crabeater Seal which dives for shorter durations and by far less deeply than the Weddell Seal, both periacinar collagen and bronchiolar smooth musculature are of similar arrangement, however, occur in considerably reduced amounts. A rich supply of autonomie nerve fibres with abundant varicosities controls the smooth muscle cells, which are interconnected by gap junctions and receive their innervation par distance (visceral type of smooth musculature). The majority of varicosities contains small clear vesicles, as is typical for cholinergic nerves, suggesting a strong parasympathetic influence. Other varicosities are presumably of peptidergic type. Mast cells and epithelial endocrine cells may exert additional influence on the musculature.     

"Circular bands" on the casts of the microcirculatory bed of the human heart in ontogenesis (data from scanning electron microscopy of corrosive casts)

By means of scanning electron microscopy of corrosive casts, applied to the human cardiac hemomicrocirculatory bed vessels, beginning from 6-9-month-old fetuses up to persons of elderly and old age, peculiarities in form, dimensions and distribution have been revealed in the wall of the arterial part of the vessels of the hemomicrocirculatory bed of so called circular strips. They are inevitable structural components in the wall of the vessels mentioned and correspond to smooth myocytes, shifted at methylmetacrilate injection.     

Modifications of Erectile Tissue Components in the Penis during the Fetal Period

Background

The penile erectile tissue has a complex microscopic anatomy with important functions in the mechanism of penile erection. The knowledge of such structures is necessary for understanding the normal physiology of the adult penis. Therefore, it is important to know the changes of these penile structures during fetal development. This study aims to analyze the development of the main components of the erectile tissue, such as collagen, smooth muscle fibers and elastic system fibers, in human fetuses.

Methodology/Principal Findings

We studied the penises of 56 human fetuses aged 13 to 36 weeks post-conception (WPC). We used histochemical and immunohistochemical staining, as well as morphometric techniques to analyze the collagen, smooth muscle fibers and elastic system fibers in the corpus cavernosum and in the corpus spongiosum. These elements were identified and quantified as percentage by using the Image J software (NIH, Bethesda, USA). From 13 to 36 WPC, in the corpus cavernosum, the amount of collagen, smooth muscle fibers and elastic system fibers varied from 19.88% to 36.60%, from 4.39% to 29.76% and from 1.91% to 8.92%, respectively. In the corpus spongiosum, the amount of collagen, smooth muscle fibers and elastic system fibers varied from 34.65% to 45.89%, from 0.60% to 11.90% and from 3.22% to 11.93%, respectively.

Conclusions

We found strong correlation between the elements analyzed with fetal age, both in corpus cavernosum and corpus spongiosum. The growth rate of these elements was more intense during the second trimester (13 to 24 WPC) of gestation, both in corpus cavernosum and in corpus spongiosum. There is greater proportional amount of collagen in the corpus spongiosum than in corpus cavernosum during all fetal period. In the corpus spongiosum, there is about four times more collagen than smooth muscle fibers and elastic system fibers, during all fetal period studied.     

Status of the circulatory bed of the vascular membrane of the eyeball and retrobulbar structures during experimental venous stasis

In 43 test animals the state of the blood bed in the retrobulbar formations and the eyeball vasular tunic has been studied under venous congestion produced by ligation of the anterior vena cava (in dogs) and both external jugular veins (in rabbits). A complex of histological, histotopographic, morphometric and variation-statistical techniques has been used. The results obtained demonstrate that disturbances in the venous outflow in the anterior vena cava system produce certain responses in all parts of the retrotubular adipose tissue, of the eyeball muscles, of the optic nerve tunics, of the vascular tunic. Certain stageness is noted in the course of venous congestion. Places of the greatest morphological changes in the eyeball vascular tunic are determined. They are zones of vorticose veins formation and the area corresponding to the posterior pole of the eyeball. The analysis of the specific areas of the intermuscular arteries and veins cross sections demonstrates that in the reaction of these vessels to the different venous outflow in the anterior vena cava system these is certain unevenness in different ofthalmic muscles.     

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.     

安徽产两种山罗花属植物及其居群叶的微形态比较

利用离析法、扫描电镜和石蜡切片法对安徽产2种3居群山罗花属植物的叶进行了微形态比较研究,结果表明：该属植物叶表皮细胞形状为不规则形,垂周壁呈波状、深波状至重波状;表皮细胞内含叶绿体;角质层具条状纹饰;表皮上有表皮毛和腺毛分布,扫描电镜下表皮毛具瘤状突起的纹饰;栅栏组织只有1层,排列比较疏松,海绵组织有发达的胞间隙;气孔器多为无规则型,极少数仅有一个副卫细胞,仅分布于下表皮,扫描电镜下气孔外拱盖内缘近光滑或浅波状。2种植物在垂周壁式样、表皮毛密度、气孔器长宽比、栅栏组织和海绵组织的厚度比以及中脉的结构特征等具有明显的差异,而山罗花3居群间的差异不明显。     

Studies onArtemisia afra Jacq.: The phloem in stem and leaf

Summary The structure of the phloem was studied in stem and leaf ofArtemisia afra Jacq., with particular attention being given to the sieve element walls. Both primary and secondary sieve elements of stem and midvein have nacreous walls, which persist in mature cells. Histochemical tests indicated that the sieve element wall layers contained some pectin. Sieve element wall layers lack lignin. Sieve elements of the minor veins (secondary and tertiary veins) lack nacreous thickening, although their walls may be relatively thick. These walls and those of contiguous transfer cells are rich in pectic substances. Transfer cell wall ingrowths are more highly developed in tertiary than in secondary veins.     

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.     

The wall structure of the central vein of the human adrenal glands]

The wall structure of the vena centralis in the human adrenal gland was examined by light and electron microscopy. The longitudinal smooth muscle system in the wall of the central vein was found to be incomplete, eccentric, and located far from the intima. At the junction with smaller veins the muscle system increases in size so that a thickening protrudes the intima into the lumen. A structured intercellular substance of varying width is located between the endothelium and the smooth muscle system, and unmyelinated adrenergic nerve fibres extend to the endothelium. Vasa vasorum are found only in the periphery of the vascular walls. The findings are interpreted as follows: The construction of the vein walls in the medulla of the human adrenal gland acts as a protection against the excessive contractile effect of a small to medium concentration of noradrenalin from the adrenal medulla.     

Microvasculature of the feline stomach

The feline gastric microvasculature was studied by corrosion of the injected vascular bed, which allowed evaluation of the vascular pattern of the different tunics. The serosal pattern consisted of numerous interconnected capillary vessels, forming a delicate network. Submucosal arteries supplied the muscular tunic through numerous anastomosing vessels that followed the direction of the smooth muscle fibers. The entire mucosal tunic was supplied by arterioles derived from the submucosal plexus; these gave rise to capillaries that surrounded the gastric glands and terminated in a diffuse, anastomosing subepithelial capillary network. Venules coursed through the mucosa in a perpendicular manner, forming submucosal veins.     

Secondary heart field contributes myocardium and smooth muscle to the arterial pole of the developing heart

The arterial pole of the heart is the region where the ventricular myocardium continues as the vascular smooth muscle tunics of the aorta and pulmonary trunk. It has been shown that the arterial pole myocardium derives from the secondary heart field and the smooth muscle tunic of the aorta and pulmonary trunk derives from neural crest. However, this neural crest-derived smooth muscle does not extend to the arterial pole myocardium leaving a region at the base of the aorta and pulmonary trunk that is invested by vascular smooth muscle of unknown origin. Using tissue marking and vascular smooth muscle markers, we show that the secondary heart field, in addition to providing myocardium to the cardiac outflow tract, also generates prospective smooth muscle that forms the proximal walls of the aorta and pulmonary trunk. As a result, there are two seams in the arterial pole: first, the myocardial junction with secondary heart field-derived smooth muscle; second, the secondary heart field-derived smooth muscle with the neural crest-derived smooth muscle. Both of these seams are points where aortic dissection frequently occurs in Marfan's and other syndromes.