DISTRIBUTION OF DNA IN HUMAN SERTOLI-CELL NUCLEOLI

For better understanding of nucleolar architecture, different techniqu es have been used to localize DNA within the dense fibrillar component (DF) or within the fibrillar centers (FC) by electron microscopy (EM) . Since it still remains controversial which components contain DNA, w e investigated the distribution of DNA in human Sertoli cells using va rious approaches. In situ hybridization (ISH) with human total genomic DNA as probe and the use of anti-DNA antibody were followed by immuno gold detection. This allowed statistical evaluation of the signal dens ity over individual components. The Feulgen-like osmium-ammine (OA) te chnique for the selective visualization of DNA was also applied. The a nti-DNA antibodies detected DNA in mitochondria, in chromatin, and in the DF of the nucleolus. ISH using human total genomic DNA showed simi lar labeling patterns. The OA technique revealed DNA filaments in the FC and focal agglomerates of decondensed DNA within the DE We conclude that (a) EM staining techniques that utilize colloidal gold appear to be less sensitive for DNA detection than the OA method, (b) the DF co nsists of different domains with different molecular composition, and (c) decondensed DNA is not necessarily confined to one particular nucl eolar component.