The aim of this dissertation was to provide a thorough description of the coronary microvasculature at different phases of cardiac contraction, during normal postnatal growth, and pathologically accelerated growth due to pressure and volume overloading. The histochemical technique used to visualize capillaries was novel in that it served to distinguish arteriolar and venular capillary regions by colour. Arteriolar capillary (AC) regions stained blue in colour, positive for the presence of Alkaline Phosphatase in the endothelium. Venular capillary (VC) regions stained red in colour, positive for the presence of Dipeptidyl Peptidase IV. The morphometric methods used to assess capillary geometry from cross and longitudinal tissue sections were classified according to AC and VC regions. From tissue cross sections, capillaries were represented as a bivariate (CV, blue; VC, red) point pattern in the tissue plane. Our software program for capillary domains served to divide the plane into polygonal regions of tissue, each polygon enclosing one capillary. The area subtended by each polygon, the capillary domain, was closer to the enclosed capillary than any other. From individual domain areas, the equivalent radius of the Krogh cylinder with the same area was calculated. As the distribution of these radii is log-normal, the variability was best characterized by the logarithmic standard deviation (SDlog). In this manner, SDlog, the heterogeneity of capillary spacing was determined. From longitudinal sections, scale drawings of capillary sets, which consisted of all the capillary pathways that could be clearly followed from the same terminal arteriole to collecting venule served as the basic unit of study. From these capillary sets, we have defined and measured several morphometric parameters, appropriate as indicators of geometrical conditions for oxygen supply. Among these parameters are the minimal capillary length, the shortest contiguous pathway from arteriole to venule; mean capillary length, the average length of all possible capillary paths from arteriole to venule; and capillary segment length, the distance between two successive capillary branch points. To illustrate the effect of changes in capillary geometry on myocardial oxygenation, we have chosen as an illustration, the results obtained from pressure overloaded hearts. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/7907 |
| Date | January 1991 |
| Creators | Batra, Sanjay. |
| Contributors | Rakusan, K., |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 273 p. |
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