RELATIONSHIP BETWEEN NUCLEOLUS AND NUCLEAR BODIES IN HUMAN MIXED SALIVARY TUMORS

The ultrastructure of nuclear bodies in human mixed salivary tumors is described in three-dimensional reconstructions. These bodies are present both in close proximity to the nucleolus as well as far from it. In the first case a dense central zone has been found directly related to the nucleolus through a connecting piece. In the second case, these bodies have a clear central zone containing microtubule-like structures, vesicles, and filaments. The transitional stages from one variety to the other is suggested. The dense central zone is granular in its structure and is extractable with cold perchloric acid in the same way as the nucleolus. The morphology, cytochemistry, and probable determining factors of these bodies are discussed in relation to similar observations reported in plant, animal, and human tissues under normal and experimental conditions. © 1969 Academic Press, Inc.