Why are the Tadpole Equations Called so?

[Kfir Dolev]

I know that the nth order tadpole equations give you the value of constant field configurations for which the first derivative of the nth order effective potential is 0, but what does this have to do with the tadpole graphs?

 

[vanhees71]

What are "tadpole equations". I've never heard this expression. Perhaps the following paper helps, where the tadpoles are resummed effectively in the Schwinger-Dyson approach:

http://arxiv.org/abs/hep-th/9603145