Complete dependence between AG NORs and C-positive heterochromatin revealed by simultaneous AG-NOR C-banding method

In the present paper we report a technique which permits the simultaneous observation of C-banded material and the active NORs or nucleoli in both mitotic and meiotic chromosomes of mammals and insects. The use of the present technique permits to establish a complete correlation between the C-banded positive regions and the presence of nucleoli associated to them. Some aspects related with this correspondence are discussed.