Our diagnostic lab had problems with a Wright Giemsa, similar results, and
found their stock (bought a case of Wright Giemsa) had exceeded their
expiration date.  A new fresh lot, within expiration date worked great.  We
sleuthed the problem as methanol evaopation which gave poor fixation and
lended to the poor staining, changes the reagent ratios even though your
buffering reagent stays the same.   

Noticed this with some old stock recently (vet research, where exp dates
sometimes are ignored!), same brand of stain, replaced with new, it worked
great - even though old lot had been stored in refrig to reduce evaporation
problems. 

Therefore, I recommend replacing your stock solution.  The more you dip
into it,open stock bottle, the more evaporation you have along with long
term storage. 

 

   


Gayle Callis
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717-3610
406 994-4705
406 994-4303