3 hpf Development
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By 78 hpf, developing cartilages of the pharyngeal skeleton, such as Meckel’s cartilage (Mk), the palatoquadrate (pq), and the ceratohyal (ch), have grown dramatically, compared to 55 hpf. Also visible are the basihyal (bh), hyosymplectic (hs), ceratobranchial (cb), copula 1 (cop1), and hypobranchial (hb) cartilages. Alizarin red staining indicates the appearance of the opercle (op) bone, derived from the second pharyngeal arch near the dorsal part of the hyosymplectic, during the third day of development. Also visible are the cleithrum (cl) bone and the coraco-scapular (cor) cartilage of the pectoral fin skeleton.