Uterine simple and complex nuclear bodies are separate structural entities.
In rat uterine luminal epithelial cells, nuclear bodies occur in the euchromatin in varying numbers in relation to the nuclear concentration of the estrogen receptor (Clark et al., 1978; Padykula et al., 1981, 1982). This functional responsiveness indicates that nuclear bodies may be useful indicators of the degree of cellular estrogenization. Because these filamentous bodies vary in size (200-1200 nm), shape, and composition, quantitative analysis of frequency of their occurrence has been difficult. A fundamental division into 2 categories can be made by the following criteria: 1) simple nuclear bodies (200-500 nm) consisting of a protein mesh of microfilaments, and 2) complex nuclear bodies (200-1200 nm) composed of an outer filamentous protein capsule enclosing a lucent core that may contain granules. Previous quantitative analyses at the electron microscopic level has excluded "simple bodies" because they might actually be ultrathin sections through the filamentous capsule of complex bodies (Le Goascogne and Baulieu, 1977; Clark et al., 1978). To resolve this sampling problem, we have performed serial ultrathin section analysis of nuclear bodies in hyperestrogenized luminal epithelial cells. Ultrastructural evidence presented here demonstrates that simple and complex nuclear bodies are anatomically separate entities. Ultrathin sections through the capsule of complex nuclear bodies will be misidentified as profiles of simple bodies during quantitative analysis. This anatomic distinctness of simple and complex nuclear bodies correlates with their differing responses to estrogenic stimulation and withdrawal (Fitzgerald and Padykula, pp. 131-141, this volume). Thus the existence of these two major categories should be taken into consideration during quantitative analyses.
D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure*; D004847:Epithelial Cells; D004848:Epithelium / Q000648:ultrastructure; D004967:Estrogens / Q000502:physiology; D005260:Female; D051381:Rats; D014599:Uterus / Q000648:ultrastructure*
D004967:Estrogens