STAINING MICROFILARIAE FOR STRUCTURES OTHER THAN NUCLEI

Oxidation and sulphation of blood films before staining has revealed the presence of “new” structures in microfilariae. Simple methods are outlined for the preparation of blood films, oxidation, sulphation, and staining with a variety of basic dyes and the more successful techniques are indicated in the text, in the tables and in the figures. After oxidation of blood films, the hook, spines and oral ring on the cephalic space of the microfilariae of Brugia and Loa may be stained by a variety of basic dyes. These structures are probably keratinous sclero-proteins and their affinity for basic dyes is due to the formation of sulphonic acid groups following the oxidation of cystine. Some of the stains reveal the presence of other structures in the microfilariae after oxidation; these include the pharyngeal thread and the posterior pores of the Schwanzgebilde. After sulphation of the blood films, the pharyngeal thread of Brugia and Loa was found to stain in a variety of basic dyes. This staining reaction is believed to be due to the formation of sulphate groups on the non-sulphated acid mucopolysaccharide component of the thread. Other structures, including tissue within the tip of the cephalic space and in the cytoplasm of two anterior cells of the microfilaria, also stain after sulphation. The additional structures in the microfilaria revealed by staining after oxidation and sulphation appear to have a characteristic combination for each genus so far investigated and they can be used to indicate relationships when the identity of a microfilaria is in doubt. © 1969 Royal Society of Tropical Medicine and Hygiene.