R edu ction ), ▁but ▁Dr . ▁Nom ura ▁developed ▁this ▁concept ▁to ▁promote ▁the ▁importance ▁of ▁control ▁of ▁the ▁environment ▁to ▁ass ure ▁reprodu ci b ility ▁of ▁the ▁results ▁of ▁animal ▁experiments . ▁ ▁Based ▁on ▁such ▁systems , ▁he ▁has ▁established ▁international ▁research ▁collabor ations ▁to ▁develop ▁three ▁animal ▁models : ▁ ▁Trans gen ic ▁Pol io ▁M ice ▁- ▁W id ely ▁used ▁in ▁pol io ▁v acc ine ▁ne uro vir ul ence ▁testing ▁as ▁a ▁replacement ▁for ▁mon keys . ▁( App ro ved ▁by ▁World ▁Health ▁Organ ization ▁in ▁March ▁ 2 0 0 3 ▁) ▁Tr angen ic ▁ras H 2 ▁M ice ▁- ▁Short ening ▁of ▁the ▁car cin ogen icity ▁test ▁period ▁in ▁drug ▁development ▁from ▁two ▁years ▁to ▁six ▁months . ▁( App ro ved ▁by ▁F DA , ▁N TP , ▁and ▁EU ▁in ▁ 2 0 0 3 ) ▁NO D / Sh i - sc id / IL - 2 R γ null ▁M ice ▁( NO G ▁M ice ) ▁- ▁New ▁generation ▁of ▁extremely ▁imm un ode fic ient ▁m ice ▁that ▁are ▁the ▁best ▁candidate ▁for ▁human ized ▁m ice ▁to ▁date . ▁ ▁Application ▁of ▁animal ▁eth ics ▁in ▁C IE A ▁C IE A ▁has ▁developed ▁animal ▁experiment ation ▁systems ▁based ▁on ▁the ▁concept ▁" s cient ific ▁animal ▁experiments ▁with ▁reprodu cible ▁results ▁can ▁not ▁be ▁achieved ▁unless ▁the ▁experiments ▁are ▁performed ▁eth ically ▁with ▁the ▁animals ▁maintained ▁in ▁a ▁normal ▁state ."