Fluorescence Microscopy for Measuring Fibril Angles in Pine Tracheids

Abstract

Observation and measurement of fibril angles in increment cores or similar small samples from living pine trees was facilitated by the use of fluorescence microscopy. Although some autofluorescence was present, brighter images could be obtained by staining the specimens with a 0.1% aqueous solution of a fluoro-chrome (Calcozine Ha vine TG extra concentrated, Calcozine red 6G extra, rhodamine 6G, rhodamine 6GD extra, or a succession of flavine and rhodamine). Staining for 2—5 min followed by a 5-10 sec washing in distilled water and drying 15 min at 190-195°C prepared radially split surfaces of specimens for microscopic observation with ultraviolet light. Measurement of fibril angles, important for the determination of wood strength and the properties of its pulp, was made with a protractor eyepiece. Photomicrography was feasible also, and the need of preparing microtome sections was obviated.