I'm trying to propose a project that including primary cerebellar neuronal cultures. I read many paper, most of them uses rat pups at postnatal day 7? Are there anyone knows why?
Earlier the granular layer is in full division. Look into the journal: Cerebellum, a lot of articles on this subject. Try to contact Prof Dr Jan Voogd, Rotterdam University, he will/can be of great help if you want to write a project.
from a purely technical point of view a development stage chould be chosen, where neurons have not yet formed axonal and dendritic processes. If working with more differentiated cells, these processes would be disrupted during preparation, even when working with gentle enzymatic dissociation. Usually this would cause cell death. At postnatal day 7 you will have a good cell harvest with a reasonable survival rate.