Immunocytochemical detection of proteins within cellular structures inaccessible to specific antibodies.

Immunocytochemistry and immunohistochemistry are among the most widely used and valuable methods for localizing and quantifying proteins in cells and tissues. However, these methods have several limitations, and they are still being improved. A notable problem in this area is the restricted accessibility of some dense intracellular structures, such as nucleoli, to specific antibodies. This reduced accessibility led to peripheral staining of the nucleoli even in cases of relatively homogeneous distribution of the antigen within the nucleoli. This review aims to elucidate the factors impeding antibody accessibility to the internal regions of the nucleolus in somatic cells and nucleolus-like bodies in oocytes and to explore the methods used to circumvent this limitation.