MMP7 and infection: We labeled a gene coding for a protein expressed by Xenopus embryonic macrophages, mmp7, that mediates extracellular matrix remodeling, a crucial aspect of their migration.11,48 Homologs of this gene-protein have been extensively used to study macrophage behavior.10,11,48mmp7-ISH was performed for the four experimental groups (Ctrl, BR–, SC–, Tail–) per each infection condition (UTI vs. NI) in st. 36 embryos.