Pathology Thread

You are now at the beginning of the RBC Basics study section.

Much of what is known of red cell development has been learned from careful morphologic observation of RBC precursors in marrow and in in vitro culture. In culture individual cells of variable maturity are stimulated to grow, forming colonies. These are referred to as colony forming units or burst forming units with the suffix E for erythroid.

Although red cell development is generally observed by cell morphology, there are sequential changes in protein synthesis and expression which can be observed as antigen expression, ie. Glycophorin A and transferrin receptor or by Northern blot of messenger RNA expression, ie globin chain expression.

As cells mature, from the most immature or blast cell to the final mature stage, they undergo numerous biochemical, structural and metabolic changes. The cytologic features of cells, as observed on Wright's stained peripheral blood and bone marrow smears, reflect such biochemical and structural developments. The general features of cell differentiation are common to most blood cells. Immature cells have delicate, fine nuclear chromatin which gradually becomes coarsely clumped or condensed. The size of the nucleus decreases; nucleoli are reduced in number or lost completely as in red cells. The nuclear shape which is initially round or oval may become uniquely confirgured as in myeloid cells. Mitotic competence is lost as cells differentiate.