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Research studies on the development of the cardiovascular system and its formation during embryologic development have been conducted for a long time. However, such studies have only gained a significant interest less than two decades ago. This can be related to the introduction of immunohistochemical methods, in which endothelium cell markers and their precursors as well as smooth muscle cell markers have been applied, lining the interior surface of a blood vessel wall of a larger diameter. In the process of coronary blood vessel formation two main mechanisms are involved: vasculogenesis and angiogenesis. The formation of vessels occurs in several stages. First a monolayer of endothelial cells begins sprouting to form tubes. These are then transformed into capillaries, veins and arteries.
The article presents atherosclerotic and inflammatory changes in brain vessels and perivascular tissue leading to ischemic and hypoxic changes which, in consequence, produce strokes and brain hemorrhages. The aim of the study was to examine the morphology of the brain vessels of seven elderly animals from 7-21 years of age (three monkeys, a likaon, wolf and two pigs). The brain vessels of the investigated animals demonstrated atherosclerotic changes such as: fibroid changes and amyloidal angiopathy (CAA) in the cortical and leptomeningeal vessels of the three monkeys, likaon and wolf brain. Fibroid arteritis was present in the meningeal arteries of the two sows. These atherosclerotic and inflammatory processes in the CNS vessels led to strokes and hemorrhages. Subarachnoid (Cebus apella) and intraventricular (Lemur mongoz) hemorrhages were noted in two of the monkey’s brains and fibrinotic arteritis produced massive mesencephalon hemorrhaging in the two 7-year old sows. The advanced stages of infarct necrosis were characterized by a predominance of vacuolated macrophages with proliferating mesodermal and glial components. Small post infarct and post hemorrhages lesions in nervous tissue produced scarring, with astrocytes, whereas large foci liquefied and formed cysts, marked by the presence of macrophages with hemosyderin in their margins. No atheromatosis changes were observed in the brain vessels.
Angiogenesis involves the formation of capillaries on the basis of already existing blood vessels. It is a multistage process resultant from the combined influence of pro- and anti-angiogenic factors. It begins with the stimulation of endothelial cells and degeneration of the basilemma and extracellular matrix, followed by the proliferation of endothelial cells and eventually the formation of a new vessel. The final stage involves a synthesis of the vessel’s basilemma and incorporation of pericytes stabilizing the capillary tube. Any study of angiogenesis necessitates a direct assessment of tissue vascularisation and indirect assessment of the occurrence of pro-angiogenic factors. The degree of vascularisation is determined on the basis of the number of capillaries and endothelial cell concentrations per a surface unit of a given tissue or organ. The same is achieved by staining histopathological samples with immunohistochemical methods using panendothelial antibodies: anti FVIII, anti-CD31 and anti CD34. The antibodies identifying proliferating endotelial cells are also specific to the evaluation of neoangiogenesis. The same include monoclonal antibodies: E9 and TEC-11. The quantitative analysis of blood vessel density in tumor tissue (MVD – microvessel density) is performed with the Weidner method. The total microvascular area (TVA) is also considered a significant angiogenic factor. The assessment of the relative surface area of capillaries within a tumor is performed using Chalkley’s method, vessel branching count (VBC) and angiogenic index. Indirect methods of angiogenesis assessment involve the determination of angiogenic cytokine production and the expression of their cellular receptors. The study of modulators and assessment of angiogenesis may facilitate more efficient tumor diagnostics and therapy
The study focused on both arterial and venous vessels of bovine testis, including the testicular artery, intratesticular arteries and veins as well as pampiniform plexus. The study involved 64 bovine testes. In 27 testes only arterial, in 22 only venous and in 15 both arterial and venous vessels were studied by corrosive method. The results of the study confirmed the majority of previous observations. The most significant novelty was the observation of variable branches of the testicular artery. The vessel originates on the posterior margin of the gonad. The most common termination of the testicular artery was a division into 2 branches of similar diameter (60%). The arterial network of the mediastinum testis was formed by vascular conglomerates in which centripetal arteries become centrifugal ones. Intratesticular arteries are winding with some short straight parts, whereas intratesticular veins are straight all along their length. The blood vessel topography of the bovine spermatic cord is very similar to that described in other mammals. On the basis of the study, the middle part of the posterior margin of bovine testis is recommended for blind biopsy of the gonad. The choice of this area reduces the risk of damage to major vessels.
Nitric oxide (NO, earlier known as EDFR - Endothelium-Derived Relaxing Factor) is a multifunctional particle involved in physiological as well as pathological reactions. The specificity of these reactions depends on the NO concentration, location and interactions with other particles. Nitric oxide affects the dilatation of blood vessels and immunological reaction. It influences cardiovascular myocyte tonus (contraction) and counteracts vasoconstrictive factors such as endothelin-1 and angiotensin-II, thereby ensuring proper tissue perfusion depending on current requirements. NO protects vessel walls by preventing lipid peroxidation and decreasing the activity of reactive oxygen radicals. Nitric oxide shows anticoagulant properties by inhibiting the adhesion, activation and aggregation of trombocytes.
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