LAUSR

Subnuclear structures such as the nucleolus have historically been studied mostly for histological interest. However, the pathological significance of the nucleolus has only been appreciated since the eighties. This was mainly due to the fact that this subnuclear organelle is not always visible by routinely used H&E-stained sections. Only enlarged nucleoli also defined as “prominent nucleoli” by pathologists are visualized by this method. In recent years, the presence of prominent nucleolar structures is one of the parameters used to define the nuclear grade of tumors by pathologists [1]. In this regard, many studies done in peripheral neuroblastic tumors have shown that MYCN gene amplification is characterized by the presence of one or more large prominent nucleoli in neuroblastic cells [2, 3]. Regarding function, it is well known that nucleoli manufacture the subunits that combine to form ribosomes; therefore, their size can be a measure of both ribosomal requirements and the physiological state of the cells. In cells synthesizing large amounts of proteins, like in proliferating cancer cells, the size of their nucleolus is considerable and sometimes occupies as much as 25 percent of the total nuclear compartment volume.