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Figure 5. A Nucleolar Genetic Marker for Xenopus laevis (Elsdale et al.11)
Heterozygotes of the one-nucleolated strain have only one nucleolus per diploid nucleus (left), compared to the wild-type 2-nucleolated form most of whose nuclei have two nucleoli (right). The one-nucleolated strain has a deletion of ribosomal genes on one chromosome.12