Resident macrophages (ED2- and ED3-positive) do not phagocytose degenerating rat skeletal muscle fibres.

Two soleus muscles with degenerating muscle fibres were serially sectioned and adjacent sections from various levels of the skeletal muscles were stained with antibodies that react with either monocytes and inflammatory macrophages (ED1) or with the major subpopulations of resident macrophages (ED2 and ED3). ED2+ and ED3+ resident macrophages were abundant throughout the muscles but were not present within the degenerating fibres. ED1+ cells, in contrast, were rarely observed within the undamaged regions of the muscles but were abundant within the degenerating fibres and in the perimysium between arterioles and degenerating fibres. It is concluded that the phagocytosis of damaged muscle fibres is not carried out by the major subpopulations of resident macrophages.