[DNA metabolism in the process of the maturation of male sex cells. I. Amplification of ribosomal genes in the spermatogenesis of rats].

It has been shown that amplification of ribosomal genes takes place in prophase I of rat spermatogenesis. At the pachytene I step, a 2-fold excess of rDNA was found. Amplification of ribosomal genes starts in the premeiotic interphase on the chromosomal DNA. At the initial stage of rDNA amplification, a rDNA-RNA hybrid was detected. Our results allow the suggestion to be made that RNA plays the role of a primer in synthesis of the excess rDNA. It is possible that AT-rich prenucleolar DNA is involved in amplification of rDNA.