Developmental stage-specific distribution of macrophages in mouse mammary gland

Abstract

12Mammary gland development begins in the embryo and continues throughout the reproductive life of 13 female mammals. Tissue macrophages (Mφs), dependent on signals from the Mφ colony stimulating 14 factor 1 receptor (CSF1R), have been shown to regulate the generation, regression and regeneration of 15 this organ, which is central for mammalian offspring survival. However, the distribution of Mφs in the 16 pre-and post-natal mammary gland, as it undergoes distinct phases of development and regression, is 17 unknown or has been inferred from immunostaining of thin tissue sections. Here, we used optical tissue 18 clearing and 3-dimensional imaging of mammary tissue obtained from Csf1r-EGFP mice. Whilst tissue 19Mφs were observed at all developmental phases, their abundance, morphology, localization and 20 association with luminal and basal epithelial cells exhibited stage-specific differences. Furthermore, 21 sexual dimorphism was observed at E14.5, when the male mammary bud is severed from the overlying 22 epidermis. These findings provide new insights into the localization and possible functions of 23 heterogeneous tissue Mφ populations in mammogenesis. 24

Guidelines for DC preparation and flow cytometry analysis of mouse nonlymphoid tissues

“…Several immune cell populations contribute to tissue remodeling [38]. Macrophages are best studied in this context [124]. Dendritic cells (DC) have also been found in MG [41][42][43].…”