Feulgen stain
（重定向自Feulgen）
![Black and white microphotograph of Feulgen stained, intact tick salivary glands infected by deer tick virus. Hypotrophied salivary acinus filled with amorphous masses of pinkstaining (=Feulgen positive) material (arrows). Scale bar = 10 µm.](/Images/godic/202501/13/Deer_tick_virus5923.jpg")
Feulgen stain is a staining technique discovered by Robert Feulgen and used in histology to identify chromosomal material or DNA in cell specimens. It depends on acid hydrolysis of DNA, therefore fixating agents using strong acids should be avoided.
The specimen is subjected to warm (60 °C) hydrochloric acid, then to Schiff reagent. In the past, a sulfite rinse followed, but this is now considered unnecessary. Optionally, the sample can be counterstained with Light Green SF yellowish. Finally, it is dehydrated with ethanol, cleared with xylene, and mounted in a resinous medium.