*4.3. Analysis of Embryo Morphology*

For histologic examination, implantation sites were fixed in Bouin's solution (Sigma), paraffin embedded, section at 10 µm and stained with hematoxylin and eosin (H&E). For each implantation site, all sections having an implantation chamber were assessed by 4 different observers for the presence or absence of morphologic traits, including primitive streak, allantois, cranial neural fold and somites, that reflect the stage of embryonic development [44]. For each pregnant dam, two implantation sites were scored.
