EFFECTS OF CRYOGENIC GRINDING ON SOFT-TISSUE OPTICAL-PROPERTIES

Optical properties obtained from spectrophotometer measurements of ref lectance and transmittance were determined for both frozen-ground and intact soft tissues. The tissues used in these experiments were calf a orta, rat jejunum, and rabbit sciatic nerve. Tissue specimens From eac h tissue type were frozen in liquid nitrogen and then ground with a pe stle and mol tar into a tine powder. A tissue paste Formed once the po wder returned to room temperature. The tissue paste was then sandwiche d between glass slides for spectrophotometer measurements. For compari son, the optical properties of the intact specimens were also measured . Total transmission and diffuse reflection were obtained on a Varian Cary 5E spectrophotometer (400-850 nm). Absorption and reduced scatter ing coefficients of the tissues were determined with the Inverse Addin g Doubling method. Our results suggested that within the 400-nm to 850 -nm spectrum, optical properties of the ground tissue approximated int act tissue within limits of experimental error. (C) 1996 Optical Socie ty of America