Localization and number of NORs (arrows) in diploid and triploid water frogs. Left column represent diploids (A–C) and right column represent triploids (D–G). Each picture is composed of a diagram of karyotype with black dots representing NORs and metaphase plates stained with silver (AgNOR), chromamycin A3 (CMA3), propidium iodide after denaturation (DPI) or after fluorescent in situ hybridization with 28S rDNA probe (FISH). A P. lessonae LL with 2 NORs, AgNORs (left) and FISH (right) B P. esculentus RL with 4 NORs on chromosome 9, CMA3 (left) and FISH (right) C P. esculentus RL with 1 NOR, AgNORs (left) and FISH (right) D P. esculentus LLR with 3 NORs, AgNORs (left) and FISH (right) E P. esculentus RRL with 4 NORs, AgNOR (left) and DPI (right) F P. esculentus RRL with 2 NORs, AgNORs (left) and FISH (right) G P. esculentus RRL with 1 NOR, CMA3.