Abstract
An RNA-ribosomal DNA complex can be isolated from ovaries of Xenopus laevis incubated in vitro during the amplification stage. A part of the RNA present in the complex is resistent to RNase but becomes completely sensitive after heat denaturation, a treatment that also allows the separation of the RNA from the DNA. The size of the RNA-ribosomal DNA complex is strongly reduced after treatment with RNase. A small fraction of the RNA present in the complex is complementary to the spacer region of the strand, which is not transcribed in vivo into cytoplasmic 18S and 28S ribosomal RNA.