STANDARD CHEMICAL FIXATIONS AS A BASIS FOR QUANTITATIVE INVESTIGATIONS OF SUBSTANCES OTHER THAN DEOXYRIBONUCLEIC ACID

Abstract

An analysis of the effect of acetic acid-ethyl alcohol (1:3) and 10% formalin on several rat tissues was made. Losses in dry weight and changes in volume of tissue pieces were followed gravimetrically. In addition, refractive index measurements on the dehydrated refractive index measurements on the dehydrated residue, as well as spectrophotometric and chemical analyses on fixation and washing solutions were carried out. It was found that formalin allows loss of some nucleotide material, some large molecular weight nucleic acid, and about 4-12% of total tissue protein (Biuret analysis). Acetic-alcohol allows loss of much lipid material, practically all small molecular weight nucleotide material, no appreciable amount of large molecular weight nucleic acids, and about the same amount of protein loss as with formalin. The embedded volume of tissues is less than the volume of the fresh tissue. Shrinkage is not simply a function of volume of extracted solids.