Glomerulus homeostasis and changes in disease: the activities of PEC podocyte progenitors. In the healthy kidney (A), PECs located at the urinary pole are proposed to produce podocyte precursors that migrate around Bowman’s capsule to replace differentiated podocytes lost during normal nephron function. The link between PECs and tubular progenitors has not yet been resolved, though in vitro evidence suggests that PECs may be multipotent, with the ability to generate podocytes and tubular epithelial cells. (B) Glomerular disease is typified by hallmark lesions in which progressive scar formation is caused by the accumulations of cells and extracellular matrix (ECM) in the Bowman’s space that can include the denuding of the glomerular basement membrane (GBM) via podocyte detachment. An advanced sclerotic lesion is depicted. The pathogenesis of glomerular disease is thought to emerge from insults to podocytes and/or the activation of abnormal PEC proliferation.