Metallic Impregnation Observations on the Metallic Impregnations of Brain Tumours

Abstract

The metallic impregnations, largely developed by the Spanish school, have greatly increased our knowledge of the morphology of the tumours of nervous tissue. Whenever we wish to trace the cell type from which a neoplasm originates we have to use a method endowed with a maximum of specificity. This specificity is found in some of the methods in which the essential feature is the selective impregnation of the cells by a heavy metal. A variety of solutions of gold and silver participate in the “modus operandi” of the methods described by Cajal, Hortega, Achúcarro and others during the first quarter of this century. The reduced silver nitrate of Cajal for the demonstration of neurofibrils, the sublimate gold chloride of Cajal for astroglia, the tannin silver of Achúcarro for reticulin and the silver carbonate of Hortega for the demonstration of Oligodendroglia and microglia are the fundamental metallic impregnations for the characterization of the different elements of the nervous tissue and they are, therefore, the methods most able to give us a clue as to the classification of a neoplasm on a morphological basis. It is somewhat more difficult to master these techniques than to stain with haematoxylin-eosin, but it is my experience that any well trained technician can produce good preparations after a few days practice.

Calvo, W., Tumores Encefalomedulares. Arch, españ. morfol. 1954.