While the focus of this review is centered upon the delineation of four nuclear structures defined by Cajal’s investigations, it is essential to acknowledge that the ensuing years have yielded the characterization of a substantial array of other nuclear subcompartments, such as Promyelocytic Leukemia (PML) bodies, polycomb bodies, clastosomes, paraspeckles or anisosomes, which are implicated in the stress response, neurodegenerative diseases and cancer reviewed in (Lafarga et al., 2002; McCluggage and Fox, 2021; Xu et al., 2021; Yu et al., 2021; Abou-Ghali and Lallemand-Breitenbach, 2024). Here, PML is linked to cancer.