FIG. 2.

Histological sections of wild-type (Wt) and ODC^−/− mutant embryos in utero. (A) Transverse section through the decidua of a normal embryo at early egg cylinder stage (E5.5). Note the appearance of the proamniotic cavity and the clearly differentiated embryonic and extraembryonic ectoderms. (B) Transverse section through a decidua of a degenerating E5.5 ODC^−/− embryo (arrow). No discernible structure can be distinguished. pa, proamniotic cavity; ee, embryonic ectoderm; epc, ectoplacental cone; eee, extraembryonic ectoderm; ve, visceral endoderm.