[Histonet] Uneven staining in same slide, any clues?

[Ze Lu]

Hi, histonet friends,

In some Ki67 staining study we have done. I always see a trend that sections in bottom half stained better than the sections in top half in the same slide. Both tissue sections are next each other during sectioning. Expect there is similar staining but always slight difference. We used hydrophobic marker pen to draw cycle to form a reservior, so the incubation should be even. Anyone has clues on it? 

Ze Lu, Ph.D.
Optimum Therapeutics, LLC