Tetracycline Staining of Tissues in Vitro

Abstract

Undecalcified sections of fresh, unfixed bones were ground to between 20 μ and 30 μ; blocks of normal and pathological liver, kidney and mammary tumour were frozen at -70 C and sections cut at 20 μ. The sections were fixed and dehydrated in absolute alcohol for 5 min and stained in an alcoholic solution of 0.5% tetracycline hydrochloride. If the sections are then immersed in 50% alcohol for 3 min, tetracycline is removed from normal soft tissues but not from pathological soft tissues. Dehydration in 70% and absolute alcohol, clearing with xylene, and covering in nonfluorescent mountant (Fluormount) completes the preparation. The sections are examined microscopically in transmitted ultraviolet light at 365 mμ. Tissues which contain tetracycline show a bright yellow fluorescence. Newly formed bone and calcined necrotic tissue, and also necrotic tissues not showing evidence of calcification, stain with tetracycline. If sections of calcined necrotic tissue are treated with decalcifying agents, until the von Kossa reaction is negative, and then immersed in the tetracycline hydrochloride they do not stain.