also , the number of rdna genes appears to be similar in adult and embryonic cells and in unreactivated and reactivated embryonic nuclei : thus , differences in reactivation rate between adult and embryonic cells , observed by us and others , can not be attributed to a gross difference in their ribosomal dna contents , and reappearance of nucleoli on reactivation can not be due to an amplification of rdna ( i.e. , to recovery of such genes if lost on terminal differentiation ) .
C0007610
nuclei
C0007609
nucleoli