ISOLATION AND CHARACTERIZATION OF MACROPHAGES FROM RAT EMBRYONIC MUSCLE CULTURE

We have previously described the wide distribution of resident macrophages in normal rat skeletal muscle. In this study, we investigated the characteristics of the macrophages that occur in rat embryo muscle cultures. We showed that cells of monocyte-macrophage lineage are present in primary muscle cultures of rat embryos (18 days in gestation) and that these cells form morphologically and phenotypically heterogeneous populations, based on their reaction with monoclonal antibodies ED1, ED2, ED3, and OX43. Constitutively Ia+ cells with dendritic appearance were also observed. Furthermore, we established the procedure for isolation of macrophages from the primary muscle cultures. The isolated cells, mostly ED1+, expressed class I and CD4 antigens and bore complement (C3) receptors on their surfaces. The fact that cell of monocyte-macrophage lineage occur in the embryonic muscle suggests that during embryogenesis these cells may enter the developing muscle and give rise to a population of tissue-associated macrophages.