New site of temporary storage of rRNA in O-mykiss previtellogenic oocytes

This article describes a new organelle found in the cytoplasm of the growth stage fish oocytes. In particular, we describe its organization at the mor phological level and investigate its composition by different cytochemical and immunocytochemical approaches with both light and electron microscope. The conclusion is that the body is a peculiar protein scaffold functioning as a temporary trap for the storage of rRNA in the mid to late growth stage oocytes. Its presence would be related to the reorganization of the mass o f amplified rDNA in micronucleoli and to the consequent temporary stop in t he rRNA synthesis. Mel. Reprod. Dev. 56:198-206, 2000. (C) 2000 Wiley-Liss, Inc.