Hello
We fix our guinne pig brains in K-dicromate for about 4hrs than we rinse then 
under running water for several hours 3hr at least, than process them. We use 
micoclear on our tissue processor. I know you asked about mouse tissue, we do 
a lot of guinne pig tissue , but also a lot of punch tissue and ear tissue 
from mice.
I hope this helps. Also the tissue once trimmed in , sits in a container of 
10% NBF for at least 24 hrs, the longer the better, we use no formalin on our 
tissue processor, we start with 70% ALC,80% ALC, 95% ALC, 95% ALC than 100% X 
3, than Microclear.
Good Luck
Sandi Miller HT
USAMRICD Research 
MD