There are three types of cells in the dark zone. 1. B-blasts (primed B cells) are small blast cells with multiple nucleoli and scant, basophilic cytoplasm. 2. Centroblasts are large blast cells with vesicular chromatin, 1 to 3 peripherally located nucleoli, and basophilic cytoplasm. 3. Centrocytes are medium-sized cells with dispersed chromatin, inconspicuous nucleoli, and scant cytoplasm that is not basophilic.