Maturation stages of plasmablasts (spleen, liver rat)

Electron microscopy. The youngest (plasmacytoid) lymphocyte in (A) shows a slight indented nucleus with a distinct nucleolus. Apart from a few mitochondria the cytoplasm contains large amount of free ribosomes and polysomes, few profiles of long rough endoplasmic reticulum (1, RER) and Golgi areas (2). The slightly more developed plasmablast in (B) has an increased amount of RER (1) and Golgi packages (2). The cell will differentiate into an antibody-producing plasma cell.