Maternal corticosterone is transferred into the egg yolk

► Increasing maternal corticosterone (cort) as a tool to increase cort in avian egg. ► Implants increased plasma cort of mothers and translated into increased yolk cort. ► HPLC analyses of the yolk extracts revealed the presence of cort in egg-yolk. ► To increase maternal cort is an efficient tool to manipulate conditions for embryos.