核仁的超微结构由纤维中心（FC）、致密纤维组分（DFC）和颗粒组分（GC）三种基本结构区域组成。
The nucleolus is made up of three basic structure subcompartments : fibrillar centers ( FCs ), dense fibrillar components ( DFCs ), and granular components ( GCs ) .
致密纤维组分