In extreme cases this appears as an undifferentiated, completely homogenous and flat, deep pink stained mass. The resolution is to reduce or eliminate acetic acid from the eosin, and use an alternate means of intensifying staining. Increasing the dye concentration or increasing the length of time for which it is applied come to mind. See the previous section. Fixation can be the cause of this kind of staining.
Different fixatives leave tissues more receptive to some dyes than to others.
Some depress staining with acid dyes, some greatly increase it. If you have introduced a new fixative, or used one for a special case, you could get this kind of effect. Check the published characteristics of the fixative used to see if this is the cause. If so, you must decide whether the reason for using the fixative outweighs the poor eosin staining, or whether a separate staining protocol for tissues fixed with that solution is necessary. Poor and inadequate fixation may also cause poor eosin staining.