Practice question

John Gurdon extended Briggs and King's earlier work by using fully differentiated somatic nuclei. Working with Xenopus laevis, he transplanted nuclei from tadpole intestinal epithelial cells into enucleated eggs and obtained normal tadpoles and adult frogs. Intestinal cells were definitive differentiated lineage possessing brush border enzymes, yet nucleus remained totipotent when placed in egg cytoplasm rich in reprogramming factors like histone chaperones and nuclear envelope disassembly machinery. Experiment proved terminal differentiation does not involve irreversible gene loss, providing key evidence for genomic equivalence and enabling later mammalian cloning strategies using adult somatic cells.