Controlled Formaldehyde-Catecholamine Condensation in Cryostat Sections to Show Adrenergic Nerves by Fluorescence

Abstract

Three sets of sections of freshly removed tissue are cut at 18 μ in a cryostat and dried on slides for 1.5 hr over P2O5. Each set of sections is incubated with a differently hydrated paraformaldehyde (prepared by storing paraformaldehyde powder over 21%, 25% or 28% aqueous H2SO4 for 1 wk) at 80 C for 1 hr before being mounted in glycerol and viewed with a fluorescence microscope. At least one set of specimens shows optimal fluorescence. The entire procedure from removing the tissue to observing fluorescence microscopically is accomplished readily within 4-8 hr. Adrenergic axons in the medial muscle of the cat nictitating membrane, the myometrium of the cat uterus and the adventitia of arterial vessels in rat pancreas are demonstrated.