Nuclear-cytoplasmic asynchrony is usually seen in :

The two principal causes of megaloblastic anemia are folate deficiency and vitamin B12 (Cobalamin) deficiency, both of which are essential factors for the synthesis of thymidylate, which is required for DNA replication. Thymidine deficiency causes abnormalities in rapidly dividing cells throughout the body, but the hematopoietic marrow is most severely affected. Because the synthesis of RNA and cytoplasmic elements proceeds at a normal rate and thus outpaces that of the nucleus, the hematopoietic precursors show nuclear-cytoplasmic asynchrony.