RESUMO

The arrangement and interconnections between various components of the aortic wall influence its physicomechanical properties and functional alterations that occur in disease and ageing. The goat is a suitable model for studying cardiovascular disease, but details of the intrinsic organization of its aorta are unknown. This study therefore investigated the histomorphology of aortic tunica media in the goat by transmission electron microscopy. Sixteen healthy juvenile and adult domestic male goats (capra hircus) purchased from livestock farms in the outskirts of Nairobi were used in the study. The animals were euthanized with overdose of sodium pentabarbitone 20mg/kg, and fixed with 3 percent phosphate buffered glutaraldehyde solution by gravimetric perfusion. Specimens obtained from the thoracic aorta (T9) were post fixed in osmium tetroxide, and prepared for durcupan embedding. Ultrathin sections stained with uranyl acetate/lead citrate were examined by EM 201 Phillips © electron microscope. Elastic and collagen fibres were structurally interconnected. Elastic lamellae, collagen and elastic fibres were linked to smooth muscle cells through areas of high electron density while smooth muscle cells were interconnected various inter cellular connections. The physical interlinkages between the components of the tunica media confer plasticity, adaptability and flexibility to the aortic wall enabling it to function as a mechanically homogenous structure. Disruptions of this structure in atherosclerosis and aging may disturb the vascular integrity and predispose to aneurysm formation.

Las relaciones e interconexiones entre los distintos componentes de la pared aórtica influyen en sus propiedades fisicomecánicas y en las alteraciones funcionales que se producen en la enfermedad y el envejecimiento. La cabra es un modelo adecuado para el estudio de las enfermedades cardiovasculares, pero los detalles de la organización propia de la aorta son desconocidos. Por tanto, se investigó la histomorfología de la túnica media aórtica en la cabra mediante microscopía electrónica de transmisión. Fueron utilizadas 16 cabras (Capra hircus) domésticas macho, jóvenes y adultas sanas, adquiridas en las explotaciones ganaderas en las afueras de Nairobi fueron utilizadas. Los animales fueron sacrificados con una sobredosis de 20 mg/kg de pentobarbital sódico, y se fijaron con una solución de fosfato de glutaraldehído al 3 por ciento por perfusión gravimétrica. Las muestras obtenidas de la aorta torácica (T9) fueron puestas en tetróxido de osmio, y se prepararon para inclusión en durcupan. Secciones ultrafinas teñidas con acetato de uranilo y citrato de plomo fueron examinados por microscopio electrónico EM 201 Phillips©. Fibras elásticas y colágenas estaban interconectadas estructuralmente. Láminas elásticas, de colágeno y fibras elásticas estaban conectadas a células de músculo liso a través de áreas de alta densidad de electrones, mientras que, las células musculares lisas estaban interconectados entre diferentes conexiones celulares. Las interconexiones físicas entre los componentes de la túnica media confieren plasticidad, adaptabilidad y flexibilidad a la pared aórtica, lo que le permite funcionar como una estructura mecánica homogénea. Las interrupciones de estas estructuras en la aterosclerosis y el envejecimiento pueden alterar la integridad vascular y predisponer a la formación de aneurismas.

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D-003 is a mixture of very-high-molecular-weight aliphatic primary acids purified from sugar-cane (Saccharum officinarum L.) wax, in which octacosanoic acid is the most abundant component. Previous experimental studies have shown that D-003 not only shows cholesterol-lowering and anti-platelet effects, but also reduces thromboxane B2 and increases prostacyclin levels. It acts by inhibiting cholesterol biosynthesis. The positioning of a non-occlusive silicone collar around the rabbit carotid artery results in the formation of a neointima. Collars were placed around the left carotid for 15 days. The contralateral artery was sham-operated. We included three experimental groups: A control group received vehicle, and two others received D-003 at 5 and 25 mg/kg until sacrificed. Samples of arteries were examined by light microscopy. To evaluate intimal thickening the cross-sectional areas of intima and media were measured. Neointima was significantly reduced in D-003-treated animals compared with controls. Furthermore, the circulating endothelial cell has been studied in this experimental model with endothelium damage. The results demonstrate the protective effect of D-003 on vascular endothelium of the studied rabbits. It is concluded that the protective effect of D-003 against neointima formation and circulating endothelial cells in this experimental model could represent potential beneficial pleiotropic effects in the anti-atherogenic profile of this substance, beyond its cholesterol-lowering and anti-platelet effects independently demonstrated.

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Pathological changes often occur in the placenta of women with sickle cell disease (SCD). These alterations are caused by sickling of erythrocytes and vasoocclusion in the placental circulation, leading to regional hypoxia. However, the morphological status of the umbilical cord, which is in close physical association with the placenta, is not documented under such conditions. To explore this, the umbilical vein structure in healthy, sickle cell trait (the heterozygous state), and SCD pregnancies was studied using scanning (SEM) and transmission electron microscopy (TEM). Interestingly, the sickle cell trait umbilical vein architecture was morphologically similar to that in control veins, whereas numerous alterations were seen in the SCD umbilical vein wall. In SEM, the SCD umbilical vein endothelial cells showed atypical morphologies. TEM analysis of the tunica media showed (1) smooth muscle cell proliferation and increase in the thickness of the basement membrane underlying the cells; (2) areas of necrosis; (3) reduplication of the inner elastic lamina. Such features were often seen in sickle patients vasculature at autopsy. Our findings could have importance because tissue hypoxemia is an integral part of vasoocclusion. We conclude that the SCD umbilical vein may be an additional tool for studying vasoocclusion in sickle cell disease.

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For the microscopical study of the great saphenous vein wall, the venous segments from six male necropsiedcadavers: were obtained three young individuals between 16 and 35 years old and three aged individuals between 50 and 83 years old. The tunica media of the great saphenous vein at the upper third level of the thigh belonging to both young and aged individuals is made up of two layers: an internal formed by fascicles of smooth longitudinal muscular fibers and the external layer made up by fascicles of smooth circular muscular fibers. At the level of the discharge in the femoral, the tunica media of the great saphenous vein wall of both, young and aged individuals, is made up of one layer, whose fascicles of smooth muscular fibers are circularly orientated in relation to the vascular axis. The tunica adventitia of the great saphenous vein wall at the upper third level of the young individuals thigh, presents elastic fibers whereas it the aged individuals it is made up of fascicles of smooth longitudinal fibers; at the level of the femoral vein disdarge in both young and aged individuals, the tunica adventitia presents a fiber elastic constitution. The young and aged individuals' parietal venous valve is elastic fiber in nature. The young individuals' ostial valve is also elastic and that of aged individuals is muscular fiber in nature.

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Se realizó un estudio secuencial de la caracterización ultraestructural, distribución y momento específico de la síntesis de algunas macromoléculas que constituyen la matriz extracelular de la túnica media de la arteria aorta de embriones de hamsters dorado (Mesocricetus auratus) de 9.5, 10.5 y 11.5 días de desarrollo. Se utilizaron marcadores catiónicos como el rojo de rutenio, el cual es capaz de retener y visualizar este material extracelular al microscopio electrónico de transmisión. Los resultados obtenidos indican que los componentes extracelulares de la túnica media aorta muestran diferencias tanto morfológicamente como en la distribución temporal y espacial durante su diferenciación. En este sentido los proteoglicanos fueron identificados como gránulos interconectados con filamentos de glicosaminoglicanos (ácido hialurónico) distribuidos entre las fibras de colágeno y elastina formando grandes agregados macromoleculares en íntima interacción con la superficie celular

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