Trypan Blue exclusion - (Apr/24/2006 )

Hi All,
I trained to isolate hepatocytes primary mouse cultures but when I stained with trypan blue there are some cells completely blue (died cells) but the 90% appear with the only nucleus blue, not cytopalsma. Have I to consider also these cells died?

If the nucleus was blue would that not imply that the dye made it through the cytoplasm? Trypan blue should only cross the membranes of dead cells. I would imagine that those cells are dead or if they are not dead yet they are dying.

Why only the nucleus is blue? Also after 5 min of exposure to typan blue the cells have only the nucleus in blue. Is because the trypan blue presents major affinity for the nucleus?
Many thanks for the answers.