Two-photon microscopy reveals stationary podocytes in living zebrafish larvae

Abstract

Podocytes are an essential component of the glomerular filtration barrier and cover the outer aspect of glomerular capillaries. Theyform a complex actin-based cytoskeleton in vivo and show prominent motility in vitro,but whether podocytes are stationary or mobile in vivo is debated. To address thi squestion, the pronephros of translucent zebrafish larvae (casper) expressing enhanced green fluorescent protein (eGFP) specifically in podocytes (wt1a:eGFP larvae) was observed by in travital two-photon microscopy over extended periods of time.Podocyte cell bodies and the interdigitating branching pattern of major processes could be resolved with are solution of approximately 1 μm in thexy-plane. Time-lapse imaging of zebrafish larvae at 5-7 days after fertilization demonstrated that podocytes neither migrated nor changed the branching pattern of their major processes over a time period of up to 23hours. In summary, we show by extended intravital two-photon microscopy that podocytes are stationary cells in the intact glomerulus of a translucent zebrafish with fluorescently-labeled podocytes.