The intra-nucleolar localization of amplified rDNA in Xenopus laevis oocytes.

A fluorescent Feulgen-stain was adapted in order to demonstrate DNA-containing structures inside the amplified nucleoli of Xenopus laevis. At all stages of oogenesis this method reveals granules or complex structures of DNA in each nucleolus. The micronucleoli which do not stain with this method and which do not reveal an internal structure in low molarity saline, unlike real nucleoli are considered as nucleolus-like bodies. The DNA-containing structures in the nucleoli can be composed of one or several granules, or they can be arranged in a linear, reticulated or circular form, independant of any correlation with the stage of oogenesis.