Fig. 2From: Conserved expression of vertebrate microvillar gene homologs in choanocytes of freshwater spongesHydroxyurea inhibits choanocyte differentiation. Addition of hydroxyurea (HU) during gemmule hatching, just prior to the differentiation of choanocytes, leads to sponges that lack choanocytes and are enriched for archeocytes, their developmental precursors. a/a’ Low- and high-magnification images a no-treatment control sponge, whereas b/b’ show comparable views of an HU-treated sponge (g gemmule)Back to article page