Rebel, H., Garssen, J., Brand, K., Kloots, W., van Unnik, A., Meijers, M., and F. De Gruijl. Monitoring of UV-Induced Oedema in the Skin of Male SKH1 Mice. ATLA. 1999. 27: 388.

One of the first reactions of mouse skin following exposure to UV light is oedema. However, assessment of threshold doses is difficult because oedema is generally poorly discernible, especially mild oedema at 48 hours after threshold dose. Apart from this complication, a more objective and accurate quantification of grades of oedema is desirable. The purpose of the present pilot experiment is to adapt an existing technique to satisfy requirements for an improved visibility and accurate quantification of oedema. Injection of a dye, for example, Evans Blue, into the circulation is known to stain the oedema through extravasation. The coulour saturation can then be used to assess the grade of oedema. A critical requirement of this technique is the reliable injection of a certain quantity of the dye into the circulation. Comparison of the three methods of intravenous injection, applied under ether anesthesia using a "bubble through system", suggested that the intraorbital injection is most easily carried out with a 100% success rate at the first attempt. Injection in the tail vein does not come close to a 100% success rate at the first attempt, which implies that uncertain quantities of the dye get into the circulation. Injection through the penis vein fully meets the requirement of a 100% success rate at the first attempt, but requires microsurgery and is consequently more tedious and requires more specific experience. This latter method is obviously more wasteful of animals because it is only applicable to the male half of an experimental group of mice. Injection of Evans Blue into the orbital plexus of hairless mice results in a distinct bluish colouration of a well demarcated area of skin that was exposed to UV radiation 48 hours earlier. This method is excellently suited for quantification of oedema reactions in the skin of hairless mice, such as those obtained after UV exposure.