[Histonet] TRAP staining and clast distribution

[Starbuck,Michael W]

Hello,

I'm doing a TRAP stain on MMA embedded undecalcified mouse tibia.  I have noticed on a few groups of slides that all TRAP positive cells are localized on or near the cortex and growth plate and there are absolutely no positive cells in the mid-cancellous region of the proximal metaphasis.  At the same time my controls work very well.   Upon repeating the stain, the results come out the same.  In my experience, I usually have TRAP positive cells show up throughout the cancellous bone.
So, is the lack of TRAP positive cells in the cancellous bone of some slides a true distribution or could it possibly be due to inadequate penetration of fixative or a problem occurring during dehydration?  Any help would be greatly appreciated.

Thanks,

Mike