A Ribonuclease-Gallocyanin Stain for Sexing Skin Biopsies

Abstract

Skin biopsies for sexing can be fixed best in 10-15% aqueous formalin or this solution saturated with HgCl₂. Bouin's fluid and all chromate mixtures should be avoided. Celloidin-paraffin double embedding is recommended but not essential. Sections are brought to water, mercurial residues removed if necessary, and then washed in distilled water. They are incubated at 37°C in a ribo-nuclease solution: approximately 1 mg of ribonuclease powder (Light's) in 100 ml of glass-distilled water; boiled 3-5 sec after dissolving, and kept in a refrigerator (usable about a week). The sections are rinsed and incubated at 37°C overnight in gallocyanin-chromalum (Einarson, 1951) made as follows: Dissolve 5 gm of chromalum in 100 ml of distilled water, add 0.15 gm of gallocyanin, shake thoroughly, heat slowly and boil 5 min; cool, filter, and wash through the filter with distilled water until the filtrate reaches 100 ml. This solution is usable at once and keeps at least a month. Sections should be dipped in acid alcohol to clean (optional), but no attempt made to differentiate them, and washed in tap water. Dehydration, clearing and covering complete the process. The method is nearly as precise as the Feulgen and more convenient and reliable for routine use on miscellaneous material.