Table 2.
Relative frequencies of STELLA+ and FOXa2+ cells in endoderm based on immunofluorescence of co-stained specimens
| Stage (N) | Staining pattern | Average number of positive cells per specimen by site (% of all counted cells)
|
||
|---|---|---|---|---|
| aPVE | HGL | HG | ||
| Early bud (1) | STELLA+ / FOXa2− | 0 (0) | NA | NA |
| STELLA− / FOXa2+ | 3 (100) | NA | NA | |
| STELLA+ / FOXa2+ | 0 (0) | NA | NA | |
| Total | 3 (100) | NA | NA | |
| Headfold (2) | STELLA+ / FOXa2− | 37.5 (32) | NA | NA |
| STELLA− / FOXa2+ | 77.5 (68) | NA | NA | |
| STELLA+ / FOXa2+ | 0 (0) | NA | NA | |
| Total | 115 (100) | NA | NA | |
| 3s (5) | STELLA+ / FOXa2− | 49.6 (31) | NA | NA |
| STELLA− / FOXa2+ | 112.6 (69) | NA | NA | |
| STELLA+ / FOXa2+ | 0.0 (0) | NA | NA | |
| Total | 162.2 (100) | NA | NA | |
| 6s (1) | STELLA+ / FOXa2− | NA | 60 (32)1 | NA |
| STELLA− / FOXa2+ | NA | 67 (36)1 | NA | |
| STELLA+ / FOXa2+ | NA | 60 (32)1 | NA | |
| Total | NA | 187 (100)1 | NA | |
| 7–10s (6) | STELLA+ / FOXa2− | NA | 24.3 (15) | 60.5 (10) |
| STELLA− / FOXa2+ | NA | 104.8 (65) | 555.8 (90) | |
| STELLA+ / FOXa2+ | NA | 32.7 (20) | 0 (0) | |
| Total | NA | 161.2 (100) | 616.3 (100) | |
1
The hindgut invagination at 6s is early in its formation, morphologically not yet distinctly formed into HGL and HG; the definitive endoderm cells counted in this specimen were grouped as HGL.
Abbreviations: aPVE, allantois-associated posterior visceral endoderm; HG, hindgut; HGL, hindgut lip; NA, not applicable, as these features were not found at these stages; s, somite pairs.