a-d, Schematic drawings of the vertebrate nephron (a), glomerular filtration barrier (b), insect excretory system (c) and nephrocyte filtration barrier (d). Ultrafiltration (red arrow), filtrate flow (black arrow) and urinary space (b) or extracellular lacunae (d) (asterisk) are shown. e,f, Drosophila garland (anti-HRP, e) and pericardial (anti-Pericardin, f) nephrocytes. Higher magnification images are shown in ei and fi. g-i, TEMs of stage 16 embryonic garland nephrocytes. g, Four garland nephrocytes surrounding the proventiculus (pv), connective fibres (arrowhead). h and i, High magnification of garland nephrocyte cell surface (h) and nephrocyte diaphragm (i) showing nephrocyte diaphragm (arrowhead), extracellular lacunae (asterisk). Scale bars 2μm (g), 100nm (h,i). fp, foot process; sd, slit diaphragm; nd, nephrocyte diaphragm; bm, basement membrane.