Kidney development begins with a population of 'progenitor cells' (green), which are similar to stem cells. Some progenitor cells (red) stream out and aggregate into a ball, the renal vesicle (gold). As each renal vesicle grows, it radically morphs into a series of shapes -- can you spot the two S-shaped bodies (green-orange-pink structures) -- and finally forms a nephron. Each human kidney contains one million mature nephrons, which form an expansive tubular network (white) that filters the blood, ensuring a constant environment for all of our body's functions.
Video courtesy of Nils Lindstorm, Andy McMahon, Seth Ruffins and the Microscopy Core Facility at the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at the Keck School of Medicine of USC