Question

Sections of fetal liver were cut at 3-4um, stained with rhodamine for 18 hours at 37*C, and then counter-stained with Mayer hematoxylin. Very little copper can be seen when the slides are examined microscopically. This is most likely because:

a. fetal liver is not a good control
b. the sections are too thin
c. the staining time was prolonged
d. the temperature was elevated

Answer 1

The most likely reason for the poor visibility of copper in fetal liver sections after staining with rhodamine is the elevated temperature during staining, which may have caused degradation or reduced efficacy of the stain.

Step-by-step explanation:

The question revolves around the observation that very little copper is visible microscopically after fetal liver sections were stained with rhodamine and counter-stained with Mayer hematoxylin. Considering the role of the fetal liver in storing copper, the staining protocol, and the biology of fetal development, it is likely that the staining time was not the issue. Fetal liver is indeed a good control for this type of staining because it stores copper. The sections are cut within the common thickness for histological studies, so it is less likely that the sections are too thin. The prolonged staining time does not usually result in reduced staining visibility, rather it could lead to overstaining. Therefore, the elevated temperature is the most probable reason. Staining procedures are generally sensitive to temperature, and excessive heat may have led to the breakdown of the stain or reduced its efficacy.