On mast-cell-mediated angiogenesis in the rat mesenteric-window assay.

Testosterone propionate injected s.c. significantly reduced the mast-cell mediated angiogenic response occurring in prepubescent rats, thereby indicating that this angiogenic reaction can be influenced by hormonal stimuli. Since the newly-formed vessels are very small, one could expect that microscopic examination would be needed to quantify the vasculature. When studying the discernment of vessels at optical magnifications of between x 100 and x 1000 in sections of methacrylate-embedded mesenteric window, we found that the number of discernible vessels increased dramatically as the magnification increased. This not only underlines the genuine microvascular character of the reaction but also demonstrates the need for high-power magnification when truly quantifying an angiogenic reaction by optical means.