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Fig. 4 jagged2 expression pattern. In situ hybridization of embryos at different developmental stages performed with the jagged2 probe. A: At the four-somite stage (4s), jagged2 is expressed in the mesoderm as shown by colabeling with the pax2a probe (see inset A′. B,C: At the 12- and 18-somite stages, jagged2 is strongly expressed throughout the brain, in the developing somites (shown at a higher magnification in E), the pronephric duct primordia, and in two clusters of cells (arrows) in the otic placode (B) and vesicle (C). D-G: At 24 hours postfertilization (hpf, D) and 30 hpf (F,G), jagged2 is expressed in the diencephalon, midbrain, and cerebellum, and with regard to the 30-hpf stage, in the ventromedial part of the rhombomeres as well. H: At 24 hpf, jagged2 is expressed strongly and diffusely in the ventral part of the spinal cord (arrows) and faintly in the dorsal part (arrowheads) but not in interneurons located in between detected by pax2a labeling. Moreover, jagged2 is also expressed in scattered cells of the pronephric duct, in which some pax2a-expressing cells are also observed. I: At 30 hpf, the jagged2 expression pattern is identical to that observed at 24 hpf, but the picture evidences the expression in the epidermis, which is out of focus in H. J1,J2: jagged2 labeling is observed in the anteroventral pancreatic anlage that expresses ptf1a and grows to engulf the endocrine pancreatic islet identified by insulin expression. K,L: At 36 hpf (K) and 48 hpf (L), jagged2 is expressed in the ear, pharyngeal pouches, and pectoral fin. Views are dorsal (A-D,F), lateral (E,G-I,K,L), or ventral (J1,J2). Anterior is to the left in all pictures. avp, anteroventral pancreas; c, cerebellum; d, diencephalon; e, ear; ep, endocrine pancreas: epi, epidermis; in, interneurons; m, midbrain; olp, olfactory placode; pep, pharyngeal endodermal pouches; pd, pronephric duct; pdp, pronephric duct primordium; pf, pectoral fin; pp, prospective pronephros; s, somites.