Terminal differentiation of erythroblasts leads to RNP segregation and formation of heterogeneous ectopic RNP-derived structures

We show an as yet unnoticed feature of mammalian erythrocyte maturation, i. e., the formation of heterogeneous ectopic RNP-derived structures in the nu cleus of erythroblasts, occurring in parallel with chromatin condensation. Inside these structures, RNPs are always recognized by specific antibodies, which demonstrates that the protein moieties of RNPs still preserve (at le ast partially) their native organization. This phenomenon shares extensive similarity with the segregation and clustering of nuclear RNPs occurring du ring spontaneous apoptosis of rat thymocytes and in several other cell mode ls in which transcription is physiologically arrested.