Acridine orange vital staining of micronucleate and amicronucleate cells. (A) Non-dividing cell with single macronucleus and a micronucleus (arrow). (B) Dividing cell with post-mitotic micronuclei (arrows). (C) Non-dividing amicronucleate cell. (D) Dividing amicronucleate cell. Distortion in dying cells (A,B,D) from typical pyriform shape (C) is normal with acridine orange and enhances visualization of micronuclei.