Microscopy, Electron, ScanningMicroscopy, ElectronPhenotypeMicroscopy, Electron, TransmissionCells, CulturedFossilsDendritesCell SizeMutationSkullPhylogenyBiological EvolutionMolecular Sequence DataTime FactorsMorphogenesisCell DifferentiationMicroscopy, ConfocalImmunohistochemistryDendritic SpinesSpermatozoaSpecies SpecificityNeuronsMicroscopy, Phase-ContrastCell DivisionActinsMicroscopy, FluorescenceCytoskeletonCell LineImaging, Three-DimensionalSperm MotilityCulture MediaAnatomy, ComparativeStaining and LabelingModels, BiologicalOrganelle ShapeCell CountSperm CountImage Processing, Computer-AssistedMandibleCell AdhesionMicroscopySurface PropertiesBiomechanical PhenomenaCell MovementMitochondriaHominidaeGreen Fluorescent ProteinsCephalometryEpithelial CellsMice, Inbred C57BLFacial BonesApoptosisPaleontologyToothGene Expression Regulation, DevelopmentalCell SurvivalLarvaInfertility, MaleCell Culture TechniquesEpitheliumFibroblastsAmino Acid SequenceHistocytochemistryAxonsOrgan SizeSignal TransductionMicroscopy, Atomic ForceParticle SizeRats, Sprague-DawleyFluorescent Antibody TechniqueMembrane ProteinsBase SequenceCell ProliferationSemen AnalysisPregnancyAnthropology, PhysicalCell NucleusCell MembraneSperm HeadDisease Models, AnimalFlowersMice, KnockoutAnimals, NewbornSemenDinosaursEmbryo, MammalianSequence Analysis, DNAMaxillofacial DevelopmentRNA, MessengerX-Ray MicrotomographyTemperatureHistological TechniquesAnimal StructuresGene ExpressionRetinaMice, TransgenicModels, AnatomicBeakTransfectionAnalysis of Variance