STUDIES ON TISSUE FIXATION: THE PENETRATION OF TRICHLORACETIC ACID SOLUTIONS INTO RAT TISSUES

A method for measuring the rate of penetration of trichloracetic acid solutions into tissues was developed and the effects of a surface active agent, temperature, and concentration of fixative on penetration rates were evaluated. Penetration distances into rat liver, kidney, and cerebral cortex were determined and expressed as a function of time. It was found the penetration distances vary directly with temperature and fixative concentration. Tergitol, a wetting agent, did not increase penetration rates into kidney or liver tissue and in high concentration actually decreased penetration into kidney. Penetration distances were found to be proportional to the square root of the time of exposure of liver to 10% trichloracetic acid solutions but this proportionality did not hold for kidney and cerebral cortex.