Transcripts become restricted to the epidermis during the extended germ band stage.
In stage 11, transcripts are detected in the entire mesoderm . EGFR signaling could be involved in modifying the inhibitory feed-back loop between neurogenic and proneural genes that exists in other neurectoderm cells. In the head midline neurectoderm, regulation of proneural and neurogenic genes has to be different. It is possible that Egfr signaling is causing the interruption of this inhibitory loop. Many cell fate decisions in higher animals are based on intercellular communication governed by the Notch signaling pathway.