Fig. 2

Developmental expression of vgl-2b. In-situ mRNA hybridisation for vgl-2b (blue/purple) shown in lateral (A, E, K, M, Q, and R) or dorsal (B, F, L, N, and S) wholemount, dorsal flatmount (C, D, G, H, J, and P; anterior to top) and transverse cryosection (I and O; dorsal to top). (A–C) Expression of vgl-2b begins at low levels at ∼7s in adaxial cells (arrowheads) as they begin to differentiate, but is absent from notochord (n). (D–I) Vgl-2b mRNA co-localises with slow MyHC-antibody staining at 14 som (arrowheads, D–I). Shown in (F) are the co-expression of vgl-2b mRNA and MyHC around similar-shaped nuclei (arrowheads) in 3.5-fold magnifications of the boxed regions in (D) (at left) and (E) (at right, reversed). Notochord expression projects rostrally beyond the first somite (arrows in D, G, and H) and extends caudally adjacent to slow muscle. (J–L) At 20 som, signal diminishes in maturing notochord but persists in the most nascent posterior regions where somitogenesis is still occurring and adjacent to the hindbrain (arrows). (M–Q) Anterior notochord expression is lost by 25 som, but continues in the tail tip (arrowheads; M, P, Q, and R). Vgl-2b mRNA persists in muscle tissue, including fast muscle (O). (R and S) At 24 hpf, as somitogenesis concludes, vgl-2b expression in muscle declines. nt, neural tube; n, notochord.