The Rapid Golgi Reaction: A Personal Quest

Abstract

In 1873, Camilo Golgi, Professor of Pavia, introduced his “reazione nera” or “black reaction” (Golgi 1873). It is a simple neurohistological procedure that consists on the fixation and staining of tissue blocks (about 9 × 7 × 3 mm). The blocks are fixed in a potassium dichromate and osmic acid solution and staining in a silver nitrate solution. The already fixed and stained blocks are cut (free hand with a razor blade) perpendicular to the gyrus long axis, into 150–250 μm thick slices, which are subsequently dehydrated in a 95% alcohol solution, cleared in oil of cloves, mounted sequentially in a large glass slide, and covered, individually, with a drop of Damar-xylene solution. After drying, the slices are ready for microscopic study. These thick preparations allow the visualization of neurons (often in their entirety), axonic terminals, synaptic profiles, glial elements, and the sprouts of growing blood capillaries of the developing brain as well as their overall interrelationships. Additional and more detailed analyses and descriptions of the procedure and some historical background can be found in Cajal (1911); Valverde (1970); and Marín-Padilla (1971, 1978a, 1990, 1992) works.