Silkie eggs. Fertilised or not?

[Emilychick]

Hi, I'm new here (and to incubating) so please bear with me.
Could someone advise whether these silkie eggs, day 5 in the incubator look as though they are fertile?
I also have bantams in the incubator which are showing some signs of veining but 5 out of 6 of these silkie eggs look exactly like this. Silkie eggs were postal, bantams were local to me.
Many thanks in advance!

 

[sourland]

I see no sign of development. Top middle - maybe I'd let go another couple of days.

 

[Emilychick]

I see no sign of development. Top middle - maybe I'd let go another couple of days.

Thank you, I'll leave them in for a little bit longer and cross my fingers!