Abstract
Staining of the acid mucopolysaccharides (AMPS) was studied in paraffin sections of the rabbit and ox corneas. Formol 4% was used as the basic fixative and was modified by the addition of different organic and/or anorganic compounds chosen either for their osmotic properties or for their supposed specific binding with the acidic groups of AMPS. In paraffin sections we did not observe any specific binding of the added salts, mainly cetylpyridinium chloride (CPC) with the acidic groups of AMPS as could be judged on the basis of their stainability. We found only the osmotic effects of these salts on the corneal stroma. Staining properties of AMPS were influenced by the level of corneal hydration achieved after fixation. In the case of normal hydration the corneal stroma stained in full width with cationic dyes both at a lower and higher pH (pH 0.5, 1.0, and 2.5). In the hydrated cornea the intensity of staining was distinctly increased at both levels of pH. On the contrary, in the dehydrated cornea the intensity of staining was suppressed, and AMPS stained only using a higher pH.