Blood Cell Nuclei: The Structure and Function of Lymphoid and Erythroid Nuclei

Abstract

Publisher Summary This chapter describes the functional organization of the nucleus and the nuclear protein matrix of lymphocyte and erythrocyte. It also presents an ultrastructure of human bone marrow cell maturation and a survey of the genome activity and gene expression in avian erythroid cells. Despite the inherent differences in nucleic acid metabolism in the developing erythroid and lymphoid lineages and in their mature cells, certain common features are also observed with respect to the structure and function of the nuclear envelope, nucleoli, nuclear matrix, and chromatin. The contribution of electron microscopic studies to the understanding of lymphoid and erythroid nuclear structure is well recognized. Studies on the mammalian and avian lymphocyte clearly indicate that for both the T and B cell lineages, fully differentiated nondividing mature cells are ultimately produced. These cells respond to an apparently infinite variety of antigenic stimuli to become proliferating cells, which participate in the immunological response. The erythroid lineage, however, yields a nondividing terminally differentiated cell, which, in the case of the mammal, expels its metabolically inactive nucleus within the sinusoids of the bone marrow hematopoietic sites and is released as the circulatory reticulocyte, ultimately becoming the fully mature erythrocyte. During the course of erythroid and lymphoid development, the proportion of dividing cells progressively decreases in parallel with marked changes in mRNA production, chromatin condensation, and overall nuclear volume.