The origin of nuclear bodies: a study of the undifferentiated epithelial cells of the equine small intestine.

During an electron and light microscopic study of the equine intestinal epithelium, it was observed that some secretory granules of the undifferentiated crypt epithelium were incorporated into the nucleus during mitosis. A study was made of the chemical nature of the granules, using standard histochemical techniques: PAS-Alcian blue, Deamination-PAS, and Ninhydrin-Schiff reactions. The granules contained a neutral protein-polysaccharide complex with many terminal amino groups, possibly an antibody (IgA). The intranuclear granules underwent coalescence and degeneration during differentiation. The end-product was identical with the nuclear bodies seen in other somatic cells and described in the literature. These nuclear bodies were seen in absorptive cells, goblet cells, and Paneth cells; but were not observed in any entero-endocrine cells. This study shows that the nucleus is capable of isolating and degrading unwanted material, foreign and internally generated, and, further, it gives an explanation for the origin of nuclear bodies, structures that have long been an enigma in cell biology.