THE USE OF A CHLORAL HYDRATE FORMALDEHYDE FIXATIVE SOLUTION IN ENZYME HISTOCHEMISTRY

Abstract

Rat kidneys were placed in formalin-saline and chloral hydrate-formalin fixative solutions and frozen sections were made at regular intervals. Five enzymes were localized by 9 different methods. In chloral-formalin fixative solution, B-glucuronidase was preserved for at least 3 weeks, acid phosphatase for 6 weeks, and esterase and lipase for 9 weeks. In formalin-saline solution, alkaline phosphatase was preserved for 23 days, while it did not last more than 1 day in the chloral-formalin fixative. These results are discussed in relation to histochemical technique and procedure, the optimum pH of the enzyme involved, and the implications for a concept of enzyme durability in fixed tissue.