V. PATHOPHYSIOLOGY

Polycythemia vera is a neoplastic disorder that originates in a hematopoietic stem cell.

Stem Cell Model of Hematopoiesis

Stem cells reconstitute hematopoiesis when transplanted into a myeloablated host.
Progenitor cells expand in the presence of growth factors and can be identified by their ability to form colonies in vitro.
Precursor cells are morphologically recognizable cells seen in the marrow aspirate.
Mature cells circulate in the blood.

Quiescent cells periodically divide, and one daughter cell returns to the Go (quiescent) state, while the other becomes committed to differentiation to a progenitor cell. With each division, the progenitor cells become progressively restricted to fewer hematopoietic lineages. Finally, morphologically recognizable precursor cells mature to produce circulating blood cells.