Table 4. Activin-induced animal cap elongation in different species combinations.
| Animal Cap | Activin (5 ng/ml)¥ | Well Elongated (%) | Stump (%) | No Elongation (%) | Sample Size (Number of Experiments) |
| lxl | — | 0 (0) | 0 (0) | 46 (100) | 46 (6) |
| 20′a | 6 (40) | 8 (53) | 1 (7) | 15 (2) | |
| 60′a | 32 (67) | 13 (27) | 3 (6) | 48 (6) | |
| 120′a | 9 (32) | 17 (61) | 2 (7) | 28 (3) | |
| [l]xl | — | 0 (0) | 1 (3) | 37 (97) | 38 (6) |
| 20′a | 7 (35) | 9 (45) | 4 (20) | 20 (2) | |
| 60′a | 21 (50) | 16 (38) | 5 (12) | 42 (6) | |
| txt | — | 0 (0) | 0 (0) | 24 (100) | 24 (4) |
| 20′a | 11 (48) | 8 (35) | 4 (17) | 23 (2) | |
| 60′a | 21 (72) | 8 (28) | 0 (0) | 29 (4) | |
| [t]xt | — | 0 (0) | 0 (0) | 21 (100) | 21 (4) |
| 20′a | 3 (17) | 7 (39) | 8 (44) | 18 (2) | |
| 60′a | 7 (27) | 13 (50) | 6 (23) | 26 (4) | |
| [l]xt | — | 0 (0) | 2 (4) | 43 (96) | 45 (6) |
| 20′b | 0 (0) | 3 (11) | 24 (89) | 27 (3) | |
| 60′a , c | 0 (0) | 45 (46) | 52 (54) | 97 (11) | |
| 60′ (25 ng/ml)a , d | 1 (4) | 19 (70) | 7 (26) | 27 (3) | |
| 120′a , e | 3 (10) | 23 (74) | 5 (16) | 31 (4) | |
| 60′ (500 pg Xbra mRNA)a , f | 4 (9) | 23 (49) | 20 (43) | 47 (5) | |
| 120′ (500 pg Xbra mRNA)a , e | 11 (29) | 20 (53) | 7 (18) | 38 (3) |
Stage 8 animal caps were treated with 5 ng/ml Activin A unless otherwise noted, for the indicated number of minutes. Where indicated, embryos were injected with 500 pg Xbra mRNA in the animal pole at stage 1. For each animal cap kind, a relationship exists between the Activin treatment and elongation. For both 20′ and 60′ Activin treatments, a relationship exists between animal cap kind and elongation (all p values<0.001; Chi-square analysis).
Row differs significantly (p<0.001) in pairwise Chi-square analysis versus its respective no Activin control.
Row differs significantly (b, p<0.005; c, p<0.001) in pairwise Chi-square analysis versus all other similarly treated animal caps.
Row differs significantly (d, p = 0.009; e, p<0.001; f, p = 0.01) in pairwise Chi-square analysis versus 60′ Activin (5 ng/ml) [l]xt treated animal caps.