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Fig. 8. NC cells are dispensable for thymus development. A: Diagram illustrating cardiac NC ablation at stage 17. B: sox10 expression in con- trol and NC-ablated embryos at stage 17 (B and E), and stage 25 (C,D and F,G). The red brackets in control (B) and NC-ablated (E) embryos indi- cate the position of cardiac NC territory ablated at stage 17. NC ablation resulted in the bilateral loss of the three most posterior NC streams at stage 25 (F,G) as compared to control (red brackets in C and D). In NC-ablated embryos, sox10 expression in the otic vesicle is unaffected (arrows). B and E are dorsal views, anterior to top. C and D (control) and F and G (NC-ablated) are showing both sides of the same embryo. Dor- sal to top, anterior to right (C and F) or to left (D and G). H: Transverse sections (dorsal to top) through two stage-47 tadpoles (H and K) following NC ablation at stage 17. foxn1 expression was detected in the thymus primordia of both tadpoles. H, J and K, M are higher magnifica- tion views of the thymi shown in I and L, respectively. I, L: The arrows point to the thymus primordia expressing foxn1. The scale bars in (B) 1⁄4 500 mm; (H, J, K, and M) 1⁄4 50 mm; (I and L) 1⁄4 200 mm. N,O: The thymi of control (n1⁄49) and NC-ablated (n1⁄49) tadpoles were dissected at stage 48 and analyzed by real time RT-PCR for foxn1 (N) and rag1 (O) expression. foxn1 and rag1 expression was normalized to the expression of the TEC-specific marker, keratin 8. Statistical significance was determined using the t-test. The values are presented as mean SEM. |
