We think that the resistance of somatic nuclei to transcriptional reprogramming by oocytes can be explained by the condensed state of chromatin. It is known that the rate of transcription increases enormously as the chromatin of nuclei transplanted to Xenopus oocytes becomes decondensed, and does so in direct proportion to nuclear volume increase [81]. As the chromatin of nuclei becomes decondensed in injected oocytes, polymerase II and other transcriptional components gain access to previously quiescent genes.
