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|Title:||Intraorgan lymphatics with special reference to the pancreas|
|Doctoral Committee Chair(s):||O'Morchoe, Patricia J.|
|Department / Program:||Biology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Pancreatic enzymes have been found in lymph but the pathways by which they enter the lymphatics is unclear. In this study a combined light and electron microscopic technique was utilized along with a morphometric analysis system to investigate the structure and distribution of lymphatic vessels in the head, body and tail portions of the rat pancreas. Serial thick sections of perfused tissue were mounted on slides, with alternate sections left uncovered to be reembedded for electron microscopy. Inter and intralobular vessels, ultrastructurally confirmed as lymphatics by the absence of both a continuous basal lamina and fenestrae, were found associated with blood vessels. Vessels with valves were confirmed as lymphatics. Valves were bicuspid and associated with basal lamina. Lymphatics directly associated with acini or endocrine tissue were rare. Quantitative data such as volume and profile densities of the lymphatics were obtained with the an image analysis system. An analysis was similarly carried out on the endothelial vesicles of the wall and valves of the vessels and on the width of the intercellular junctions. Such information is necessary to understand the cellular transport mechanisms responsible for lymph formation.
It has been reported that there are enzymatic differences between blood and lymphatic endothelium. For example, it has been indicated that at the light microscopic level, alkaline phosphatase activity is present only in blood capillary whereas 5$\sp\prime$nucleotidase may be detected in both types of capillaries. This study was designed to examine these enzymatic differences at the light and electron microscopic level. Staining of tissues from rat thyroid, heart, pancreas and kidney was carried out. Alkaline phosphatase reaction product was found in 90% of blood capillaries. However, it was also found in the endothelium of 33% of lymphatics. 5$\sp\prime$nucleotidase activity was present in all lymphatics and in 75% of blood capillaries. Although this study supports observations made at the light microscopic level, it indicates that the enzyme activity is not as specific as previously suggested. The level of enzyme activity may, in fact, vary with differing degrees of activity of individual vessels.
|Rights Information:||Copyright 1990 Navas, Vivian|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9021733|