Structural and functional relationships between nuclear bodies and the nucleolus-DNA body complex in the oocyte of...

The localization, structure and function of two types of nuclear bodies have been investigated by cytological and cytochemical electron microscopy methods in oocytes from the Hoplonemertean, Amphiporus lactifloreus. Type I nuclear bodies differentiate in contact with the nucleolus-DNA body complex, whereas type II nuclear bodies develop close to the diplotenic chromosomal axes. The structure of type I and type II spherical nuclear bodies, 4-5 micron in width, results from the association of a fibrillar reticulum with some dense included regions. The cytochemical findings following the use of osmium-ammine reaction for DNA and silver reaction for NOR proteins support the hypothesis that type II nuclear bodies, derived from the extranucleolar area, as well as type I nuclear bodies, derived from the nucleolar complex, may be involved in ribosomal biogenesis.