Figure 3.

B cells from Eμ-c-myc mice are enlarged during all phases of the cell cycle. (A) Purified splenic B lymphocytes isolated from Eμ-c-myc or littermate control mice were stained with PI, and cell cycle status was determined by flow cytometry. Shown is a representative single-parameter flow cytometric histogram. (B) FSC were determined for purified splenic B cells that fell within G₀/G₁, S, or G₂ gates, as outlined by using PI staining in A. The biphasic G₀/G₁ peak likely represents separation of G₀- and G₁-phase cells. G₀-, G₁-, and G₂-phase cells from Eμ-c-myc mice exhibit higher FSC than similar phase cells from littermate control mice. (C) Splenic B lymphocytes were purified, fixed in ethanol, and stained with PI (see Materials and Methods). G₂-phase cells (50,000 cells) from Eμ-c-myc and littermate control mice were sorted by flow cytometry, and cell volume was determined by using the Coulter principle. (Ethanol fixation results in a significant, but proportional, reduction in cell size.)