Electron micrograph of macrophages from wild-type and C/EBPε knockout mice.

(Upper panel) Wild-type bone marrow (BM)–derived macrophages that have abundant rough endoplasmic reticulum (R) and numerous primary (small arrowheads) and larger secondary lysosomes (large arrowheads) (×6000). In contrast, the knockout macrophages have fewer cisternae of rough endoplasmic reticulum and a paucity of secondary lysosomes (×8050). (Lower panel) Ultrastructure of wild-type thioglycollate-elicited macrophages (PL) and C/EBPε knockout cells (right)