If you seem at Eva as a tale whose protagonists are Gendo and Fuyutsuki, then the heroine would be Yui Ikari. And the images of that flashback are the scene of the experiment from Episode 20-1 "NERV Is Born," in which Yui Ikari is the subject matter. It is explained that the oral stage starts off at start and ends close to the age of one 1/2.