Interrelationship Between PO2, Morphology and Perfusion in Rat Mammary Adenocarcinoma (AD) Using Combined in Vivo Microcathode/India Ink Injection/Freeze Substitution Techniques
A knowledge of oxygen tension (pO2) distribution in neoplasia is fundamental to understanding relationships between tumor necrosis and perfusion. The exploration of in vivo oxygen distribution was pioneered by Vaupel (1). However, to our knowledge tumor oxygen profiles have not been related to tumor structure. Combining an oxygen recessed microcathode and freeze exchange technique has permitted correlation of in vivo tumor pO2 profiles with structure from permanently fixed tissue sections. This freeze exchange process provides representative in situ dimensions by in vivo quick freezing, but as yet does not produce thin (< 8 micron) sections. Histologic evaluation of 25–50 micron stained sections did not clearly show the distribution of small vessels and capillaries, but did reveal that our tumor model had necrotic regions often containing apparent vessels surrounded by viable tumor cells. In addition, there is increasing evidence supporting the observation that neoplastic vascular function may be inhomogeneous (2–6). Therefore, we developed an in vivo india ink injection/freeze exchange technique to demonstrate representative in situ vascular distribution and apparent tumor perfusion. Selected tumors in the experimental series were india ink injected and serial sections of the tumor were compatible with the pO2 profiles.
KeywordsMethyl Salicylate Rapid Freezing Necrotic Region Oxygen Profile Environ Exercise
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