Whole mount in situ hybridization of mustn1a at (A-B) 7-somite stage, (C-D) 15-somite stage, (E) 24 h post-fertilization (hfp), (F) 48 hpf, and (G) 72 hpf. (A) Lateral view of must1a expression at 7-somites. (B) Expression of mustn1a in Kupffer′s vesicle (arrowhead). (C) Lateral view of must1a expression at 15 somites with dorsal view in (D). (E) Lateral view of mustn1a expression at 24 hpf. (F) Lateral view of 48 hpf embryo. ov = otic vesicle, f = fin bud. (G) Lateral view of 72 hpf larva with mustn1a expression in the posterior blood island (pbi). Scale bar = 200 µm.

Whole mount in situ hybridization of mustn1b at (A-B) 7-somite stage, (C-D) 15-somite stage, (E) 24 h post-fertilization (hfp), (F) 48 hpf, and (G) 72 hpf. (A) Lateral view of must1b expression at 7-somites. (B) Expression of mustn1b in Kupffer′s vesicle (arrowhead). (C) Lateral view of must1b expression at 15 somites with dorsal view in (D). (E) Lateral view of mustn1b expression at 24 hpf. mustn1b mRNA was detected in the heart tube (h) and slow muscle pioneer cells (pc). (F) Lateral view of 48 hpf embryo with mustn1b expression in the outflow tract (ot) and low level of expression in the otic vesicle (ov). (G) mustn1b expression in 72 hpf larva with mRNA detected in the branchial arches (arrow). Scale bar = 200 µm.

Expression of mustn1a (A-B) and mustn1b (C-D) 120 hpf (5 days post-fertilization). (A) Lateral view of mustn1a with pronounced expression in the otic capsule (oc), neurocranium (nc), and gut (g). (B) Dorsal view of head region showing mustn1a mRNA in the developing neurocranial structures. (C) Lateral view of mustn1b with expression in the otic capsule (oc), neural cranium (nc), ceratohyal (ch), and ceratobranchial (cb). (D) Dorsal view of head showing mustn1b mRNA distribution in developing skeletal structures. Scale bar = 200 µm.