Stage-dependent actions of Tbx5 and Tbx4 in limb initiation
| A Effect of CAGGS-Tbx5 . | . | . | ||
|---|---|---|---|---|
| Stage of injection . | Total . | Number of wing-like extra limbs . | ||
| 8 | 8 | 0 (15%) | ||
| 9 | 15 | 2 (13%) | ||
| 10 | 14 | 7 (50%) | ||
| 11 | 15 | 7 (47%) | ||
| 12 | 15 | 1 (7%) | ||
| 13 | 13 | 0 (0%) | ||
| 14 | 10 | 0 (0%) | ||
| 15 | 8 | 0 (0%) | ||
| Totals | 103 | 19 | ||
| A Effect of CAGGS-Tbx5 . | . | . | ||
|---|---|---|---|---|
| Stage of injection . | Total . | Number of wing-like extra limbs . | ||
| 8 | 8 | 0 (15%) | ||
| 9 | 15 | 2 (13%) | ||
| 10 | 14 | 7 (50%) | ||
| 11 | 15 | 7 (47%) | ||
| 12 | 15 | 1 (7%) | ||
| 13 | 13 | 0 (0%) | ||
| 14 | 10 | 0 (0%) | ||
| 15 | 8 | 0 (0%) | ||
| Totals | 103 | 19 | ||
| B Effect of CAGGS-Tbx4 . | . | . | ||
|---|---|---|---|---|
| Stage of injection . | Total . | Number of leg-like extra limbs . | ||
| 8 | 8 | 0 (0%) | ||
| 9 | 15 | 4 (27%) | ||
| 10 | 12 | 5 (42%) | ||
| 11 | 18 | 6 (33%) | ||
| 12 | 16 | 2 (13%) | ||
| 13 | 12 | 0 (0%) | ||
| 14 | 10 | 0 (0%) | ||
| 15 | 10 | 0 (0%) | ||
| Totals | 92 | 17 | ||
| B Effect of CAGGS-Tbx4 . | . | . | ||
|---|---|---|---|---|
| Stage of injection . | Total . | Number of leg-like extra limbs . | ||
| 8 | 8 | 0 (0%) | ||
| 9 | 15 | 4 (27%) | ||
| 10 | 12 | 5 (42%) | ||
| 11 | 18 | 6 (33%) | ||
| 12 | 16 | 2 (13%) | ||
| 13 | 12 | 0 (0%) | ||
| 14 | 10 | 0 (0%) | ||
| 15 | 10 | 0 (0%) | ||
| Totals | 92 | 17 | ||
(A) Tbx5 was misexpressed by in ovo electroporation at various developmental stages. Wing-like additional limbs were induced only when electroporation was performed at stages 8 to 12.
(B) Likewise, formation of leg-like additional limbs was observed only when Tbx4 was misexpressed at stages 9 to 12, setting up a short critical period from stages 8 to 12.