Page 15 - Effects of radiotherapy and hyperbaric oxygen therapy on oral microcirculation Renee Helmers

General introduction and outline of the thesis
ORAL MICROCIRCULATION 1
The microcirculation consisting of the smallest vessels in the circulatory system (<100 micrometers; e.g., arterioles, capillaries, venules) serves an important function in delivering and removing constituents to and from tissues. Gas exchange (CO2 and O2) and management of nutrients and waste products are prerequisites for maintaining tissue health and to resist or manage pathological processes. Derangement in microcirculation can jeopardize the healing capacity and consequently result in pathologies. Interpreting early alterations diagnostically in tissue microcirculation (organ, sublingual) is an ongoing goal in a broad field of research with the aim of defining clinical targets of therapy and timing of treatments at the patient bedside. By harnessing the diagnostic value of the microcirculation, it would be possible to improve microcirculatory indices and hereby patient outcome and treatment success.18,37,42 An advantage of the HN region is that the oral mucosa provides a direct window into the region of interest.
The oral mucosa lines the oral cavity and has varying thicknesses in epithelium (keratinized and non-keratinized) between the different oral tissues. The underlying connective tissue (lamina propria) consists of a papillary layer and a reticular layer. Ascending arterioles extend from the reticular layer of horizontal vascular network into the papillary layer, form capillary loops that arch towards the epithelium and then continue descending down into the venous system in the reticular layer and subsequently into submucosa. The submucosa consists of loose connective and fatty tissue, larger blood and lymphatic vessels, salivary glands and nerve fibers.
Different anatomic regions and their associated microcirculation can be identified when studying the oral cavity with handheld vital microscopy (HVM). Sprouting capillary loops originating from the deeper reticular layer are organized as an array of capillary loops below the epithelial surface and in the papillary layer of the lamina propria of the oral mucosa, e.g., the lip, the gingiva [Fig. 1] and the buccal lining mucosa [Fig. 2].
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