Nucleolar Vacuoles in Living Normal and Malignant Fibroblasts

Nucleolar vacuoles can frequently be seen in living normal and malignant fibroblasts of rats and mice in our hanging drop cultures. They are probably similar to the "nucleolar or intranucleolar vacuoles or bodies" noted by various authors in many different types of animals. Since the origin and significance of nucleolar vacuoles is unknown, I attempted to determine if there were any correlations between their occurrence and some cultural or cytological characteristics of normal and of malignant fibroblasts. No consistent ones were found. I also attempted to determine if there were significant differences between normal and malignant fibroblasts in cultures in regard to the number of cells with nucleolar vacuoles, the number per nucleolus, and their size. No differences were found except that an occasional sarcoma had relatively more cells with them and more vacuoles per nucleolus than were found in cultures of normal fibroblasts.