The results of sequential treatments for Ag-NORs polymorphisms in Monopterus albus are reported. Four types of Ag-NORs polymorphisms, varying in form, number, and location haw been detected respectively. The Ag-NORs polymorphisms were individually specific, and the distributions of Ag-NORs, secondary constrictions and positive C-bands were coincident. The mechanism of Ag-NORs polymorphisms and their relatio...