Although intense staining for MCP-1 is observed in both the regressing corpora lutea of cycling rats and the corpora lutea of hypophysectomized rats treated with prolactin, we observe differential expression of cell markers for monocytes/macrophages in these animals. In hypophysec-tomized rats, although the number of monocytes/macrophages per high-power field is greatly increased by 72 h after onset of prolactin treatment, virtually none of these cells are positive for the ED2 antigen (based on personal communications). In contrast, in the current study we observed large numbers of ED2-positive cells, up to two thirds of the entire ED1-positive population. buy yasmin online
Expression of the ED2 antigen correlates with differentiated, resident macrophages, and adhesion is necessary to induce its expression. The ED2 antigen is not expressed on monocytes, nor is it expressed on recently recruited inflammatory macrophages, which may explain the lack of staining in corpora lutea of rats treated with prolactin. According to van Rooijen et al., it may take a week for ED1-positive cells to express the ED2 antigen.