Comparative morphological and histochemical aspects of selected arteries in the chicken and rat

A quantitative study of the aorta of the chicken (Gallus domesticus)

The different segments of the aorta were studied quantitatively in five age groups of chicken. It was observed that the widest diameter and the thickest media occur on the 56th day in each segment, except for the thoracic aorta, which had the widest diameter on the 42nd day and the thickest media on the 70th day. The percentage of the intima, media and the adventitia, as compared with the total wall thickness, was determined and it was found that this value was quite similar in age group, but the differences were significant from one segment to another. The ratio between the total wall thickness and the lumen diameter was also calculated in each segment.

Age-related modification of average volume and anisotropy of vascular smooth muscle cells

The aim of this study was to determine what changes in the arterial wall are related to age. In two groups of rabbits, one young and one adult, the aorta and carotid were studied using a morphometric approach based on stereological axioms and planimetric morphometry. The problem of anisotropy of smooth muscle cells is discussed in detail. Two forms of anisotropy must be distinguished, that of single cell and that due to the histological pattern of the smooth muscle cells in the arterial wall. Our results show in adult animals, as compared to the young ones, statistically significant decrease in anisotropy of the cell pattern which tends to become more regular. Moreover, in aorta and carotid of young and adult animals there is an increment of 95.39% and 80% of the absolute cell volume, respectively. We suggest that there may be a direct relationship between aging and phenotypical modulation of the smooth muscle cells and that the modification of the architectural cell pattern with age may represent an adaptive event related to the change in forces acting upon the arterial wall.

Morphometry of the amount of smooth muscle cells in the media of various rabbit arteries

Our objective in this study was to evaluate the relative amount of smooth muscle cells in the medial layer of various rabbit arteries. The fixation of smooth muscle cells in the arterial wall is difficult and the differential effect of glutaraldehyde (GA) and fixative vehicle on cell ultrastructure in different tissues is controversial. We compared the effect of various concentrations of the vehicle and glutaraldehyde (osmolarity ranges for total fixative, 350-1030 mOsm) on the arterial wall ultrastructure. We found that a 600 mOsm GA solution (isotonic vehicle; 2.5% GA) adequately preserves arterial wall structures. The relative amount of smooth muscle cells in the media differed in various segments along the arterial tree. It ranged from 35% (thoracic aorta) to 74% (tibial artery). The importance of weighting the contractile response of different arteries in vitro to their relative smooth muscle cell content is discussed.

The myocardium and its vasculature: a histochemical comparison of the normal and chronically sympathectomized dog heart

Using histochemical techniques, the reactivities of selected enzymes and other metabolic components were examined in the myocardium, coronary arteries, and coronary arterioles of normal, two-week-sympathectomized, and sham-operated canine hearts. There were no differences in the histochemistry of coronary arteries in any of the hearts, but important differences were noted in the myocardium and especially in the arterioles. The reactivities of the enzyme glucose-6-phosphate dehydrogenase and the nucleic acids were increased in arterioles of the sympathectomized heart, possibly indicating an increased protein synthesis. The reactivities of succinate dehydrogenase, NAD-isocitrate dehydrogenase, and cytochrome oxidase were reduced in myocardium and arterioles of sympathectomized hearts as well as in arterioles of sham-operated hearts; the changes were greater in the sympathectomized arterioles where there was also observed an increase in reactivity of lactate dehydrogenase. These findings suggest a depression in aerobic metabolic capacity and, in the case of the sympathectomized arteriole, imply a possible shift in adaptation from aerobic to anaerobic metabolism.