Hi all !
I have a small problem ! when i fix my 6 and 12 somite stage zebrafish
with 4%PFA overnight at 4degrees, the yolk sac becomes dark brown when
i look it under the microscope the next day. I was them in PBT (PBS+
Tween) and store in 100% MeOH for ISH. The embryo however, remains
clear. Can anyone please tell me why this happens and how can I
prevent it ? I have checked my PFA solution, and it seems to be fine.
please help !