Fig. 3

 Embryonic expression patterns of insm1a (A, A′, D, D′, F, F′, G, and H) and insm1b (B, B′, E, I, J, and K). At 10 hpf (A, A′, B, B′, C, and C′) shortly after neurogenesis has been initiated, insm1a is barely detectable in the lateral trunk while insm1b is expressed in a broader range of presumptive trunk neurons, as shown by similarities to expression of the proneural gene deltaA (C, C′, L, M, and N). (A–C) Anterior expression while A′, B′, and C′ show trunk expression of the same embryo. At 14 hpf (D, D′, and E) insm1a is visible in a disorganized manner in the rostral trunk region (inset D′), presumably pancreatic progenitors. insm1b is clearly visible in the presumptive trigeminal ganglia (E). By 24 hpf (F, F′, I, and L) it is evident that both insm1a and insm1b are expressed in a subset of proneural, deltaA-positive cells. Ventral endoderm in the rostral trunk shows a clustering of cells expressing insm1a (inset F′). At 48 hpf (G, J, and M) both insm1a and insm1b are visible throughout the CNS and expression in the spinal cord is no longer detectable. Expression is also seen as dorsoventral stripes in the hindbrain. Retinal expression of insm1a is prevalent at 48 hpf, however by 72 hpf (H, K, and N) it is restricted to a subset of cells, consistent with a transient process such as neuronal differentiation or maturation. Scale bars represent 100 μm. Inset images were taken of flat mounts of the same embryo shown in its respective panel. cb, cerebellum; cg, cranial ganglia; d, diencephalon; ep, epiphysis; hb, hindbrain; mb, midbrain; olf, olfactory placode; ot, otic vesicle; r, rhombomere; ret, retina; scn, spinal cord neurons; tec, optic tectum; teg, tegmentum; tel, telencephalon; tg, trigeminal ganglia; and tn, trunk neurons.