TABLE 1.
Summary of placental phenotypes at E9.5a
| Genotype | No. of fetal vesselsb | Chorioallantoic fusionc | Invasiond | Tpbp+e | PI 1+f |
|---|---|---|---|---|---|
| Arnt+/+ | 12 | + | +++ | +++ | +++ |
| Arnt−/− | 0 | − | − | − | ++++ |
| Hif1α+/+ | >25 | + | +++ | +++ | +++ |
| Hif1α−/−g | 4 | + | ++ | ++ | +++ |
| Hif1α−/−g | 0 | − | + | ++ | +++ |
| Hif2α+/+ | >15 | + | +++ | +++ | +++ |
| Hif2α−/− | 10 | + | +++ | +++ | +++ |
| Hif1α−/− | 0 | − | + | + | ++++ |
| Hif2α+/− | |||||
| Hif1α−/− | 0 | − | − | − | ++++ |
| Hif2α−/− |
Most embryos examined had approximately 20 somites when harvested, except Hif1α−/− Hif2α+/− and Hif1α−/− Hif2α−/− embryos, which had between 6 and 8 somites.
Average number of fetal blood vessels in the labyrinthine layer.
Absence (−) or presence (+) of chorioallantoic fusion.
Extent of maternal tissue invasion: very poor (−), poor (+), good (++), very good (+++). Morphometric analysis revealed that Hif1α−/− Hif2α−/− placentas exhibited a 17% decrease in invasion distance, while Hif1α−/− Hif2α+/− exhibited a 5 to 8% decrease.
Extent of Tpbp expression: little to no expression (−), greatly diminished (+), reduced (++), good (+++).
Extent of PI 1 expression: normal expression (+++), increased expression (++++).
Chorioallantoic fusion occurred in 69% of the Hif1α−/− embryos and was not detected in the remaining 31%.