Fig. 2. Invasion of MDCK-G cells in pre-cultured chick heart fragments. Sections of confrontation cultures of MDCK-E cl3 control cells (A and B) and MDCK-G cl6 (C and D) cells, fixed after 7 days and stained with hematoxylin–eosin (A and C) or with antiserum against MDCK cells (B and D). Black arrowheads in (A) and (B) mark MDCK-E cells. White arrowheads in (C) and (D) mark invasive MDCK-G cells. Bar = 100 µm.