Table 1. Effects of RA on endoderm marker gene expression.
| Application | [RA] | Cyp26A1 | HoxA2 | HoxB4 | Hex | Nkx2.1 | Prox1 | γ-fibrinogen | Pdx1 | CdxA |
| Graft at gastrulastage (HH 4) | ||||||||||
| Bead graft | 10−3 M | 6/6 | ND | 1/1 | 7/7 | 6/6 | ND | ND | 0/5 | 0/2 |
| 10−4 M | 4/4 | ND | 8/8 | 5/6 | 5/5 | ND | ND | 0/8 | 0/1 | |
| control | 2 | ND | 4 | 9 | 12 | ND | ND | 6 | 2 | |
| Culture med | 10−6 M | 2/4 | ND | 0/4 | 3/3 | 2/2 | ND | ND | 0/5 | ND |
| 10−7 M | 0/3 | ND | 0/5 | 3/3 | 1/1 | ND | ND | 0/4 | ND | |
| control | 2 | ND | 3 | 3 | 1 | ND | ND | 6 | ND | |
| Graft at somite stage (HH 10) | ||||||||||
| Bead graft | 10−3 M | 8/8 | 6/6 | 17/17 | 5/5 | 2/2 | 6/6 | 0/3 | 0/18 | 0/15 |
| 10−4 M | 7/7 | 6/6 | 5/5 | 5/5 | 3/3 | ND | ND | 0/21 | 0/8 | |
| control | 10 | 4 | 16 | 4 | 3 | 3 | 2 | 13 | 8 | |
| Culture med | 10−5 M | 1/1 | ND | ND | 5/5 | ND | ND | ND | 0/5 | ND |
| 10−6 M | 4/7 | ND | 3/4 | 2/6 | ND | ND | ND | 0/21 | 0/3 | |
| 10−7 M | 0/6 | ND | 0/4 | 3/8 | ND | ND | ND | 0/23 | 0/3 | |
| control | 8 | 10 | 5 | 14 | ND | ND | 3 | 26 | 3 | |
Stage indicates the stage of treatment; Bead graft, grafting of RA-soaked beads; Culture med, RA was applied to the culture medium; ND, not done;
Phenotypes: Cyp26A1, concentration-dependent induction around the bead; HoxB4 and HoxA2, anterior expansion of the domain & increased levels of expression; Hex, comprise embryos collected at HH 5–6 and HH 14; at HH 5–6, Hex is partially repressed and at HH 14, Hex is inhibited in thyroid domain, liver domain remains unaffected; Nkx2.1, inhibited thyroid expression; Prox1, repression close to the bead. γ-fibrinogen, Pdx1 and CdxA, no effect.