Fig. 2. lsn mutation affects both craniofacial and thymus development. (A-D) Alcian Blue staining showing pharyngeal cartilages in 120 hpf wild-type (A,C) and lsn mutant (B,D) larvae shown in lateral (A,B) and ventral (C,D) views. In lsn, the development of the pharyngeal cartilages is abnormal. Notably the ceratobranchials 4 and 5 are absent in lsn. cb 1-5, ceratobranchial cartilages 1-5; ch, ceratohyal cartilage; hs, hyosymplectic cartilage; m, Meckel's cartilage; pq, palatoquadrate cartilage. (E,F) rag-1 expression at 96 hpf in wild-type (E) and lsn mutant (F) larvae shows that lsn embryos have a significantly reduced thymic primordia (arrows).