Effect of DAPT on somite formation

[Sannsibal]

Hi,

last week in a lab class, we applied DAPT to 3 day old chicken embryos and measured the time until extra pairs of somites formed.
In the assessment, there is the question "Why should DAPT affect somite formation?".

Now, I've read that DAPT blocks Notch signalling pathways, and that this pathway is important for the formation of the anterior-posterior identity of individual somites. But why do extra somites form as a result of DAPT treatment? Does Notch signalling affect not only the orientation, but also the number of somites?
Anybody knows anything about this?

Thanks a lot.