Animals, NewbornAgingFetusAge FactorsLiverRNA, MessengerRats, Inbred StrainsInfant, NewbornPregnancyEmbryonic and Fetal DevelopmentGestational AgeGene Expression Regulation, DevelopmentalBrainRats, Sprague-DawleyTissue DistributionOrgan SpecificitySpleenKidneyRetinaImmunohistochemistryTime FactorsMice, Inbred C57BLNeuronsMice, Inbred BALB CTranscription, GeneticBase SequenceCells, Cultured