Macrophage density in the pregnant rat uterine cervix is modulated by mast cell degranulation

The uterine cervix at term undergoes histomorphological changes that resemble an inflammatory process. The aim of this study was to better characterize these changes, describing the temporal and spatial pattern of macrophages and mast cells (MC) distribution in the uterine cervix and assessing whether both cells exert a coordinated action on angiogenesis. Macrophages and MC were identified by immunohistochemistry in cervical tissue from cycling, pregnant and postpartum rats. In order to inhibit MC degranulation, pregnant rats were injected with disodium cromoglycate. The expression of vascular endothelial growth factor (VEGF) by macrophages was also evaluated. Results showed that macrophage density increased towards parturition and declined at postpartum, whereas MC density showed an inverse pattern. Interestingly, disodium cromoglycate-treated rats showed an increased number of macrophages. VEGF expression in macrophages was detected neither in control nor in treated animals; however, a coordinated action between MC and macrophages on angiogenesis could not be excluded. The present study provides a detailed mapping of macrophage and MC densities and distribution in the rat uterine cervix. Moreover, an association between macrophages and MC along pregnancy is shown, and evidence that macrophage density in the rat cervix is modulated by MC degranulation is presented.