Lecture 18: Embryo DevelopmentTiming of InseminationErrors in FertilizationErrors in Fertilization (cont.)Slide 5Oocyte Development and FertilizationPowerPoint PresentationEmbryo Development in the BovineFertilization to CleavageSlide 10ImprintingSlide 12Gene Control of DevelopmentSlide 14Slide 15Precompaction CleavageSlide 17Slide 18Cell Cycle LengthsSlide 20Slide 21Asynchronous Cleavage - Inside Outside TheoryAsynchronous Cleavage UseSlide 24Slide 25Transition from Maternal to Embryonic Gene ControlSlide 27Slide 28Movement into the UterusSlide 30Early Pregnancy FactorMorula to BlastocystPolarizationPolarization (cont.)Cell LinageCompactionBlastocyst Formation and HatchingBlastocoel FormationSlide 39Slide 40Slide 41Slide 42Formation of TwinsFormation of Monozygotic TwinsUpdated:01/14/19 Lecture 18: Embryo DevelopmentAnimal Science 434John ParrishUpdated:01/14/19 Timing of InseminationSpecies Time of Ovulation Optimal Insemination TimeCow 29 hr after start End of estrus (12 hr afterof estrus first seen in estrus)Ewe End of estrus End of 1st day or start of2nd day of estrusSow End of estrus End of 1st day or start of2nd day of estrusMare 1-2 days before Every other day beginningend of estrus day 3 of estrusUpdated:01/14/19 Errors in Fertilization•Polyspermy - polyandry»Multiple sperm penetration»Invertebrates•excess sperm eliminated because sperm centriole contributes to first embryonic cleavage spindle»Mammals•Sperm centriole not essential so development continues but fails early to midpregnancy due to multiploidy•Occurs most often in aged oocytes due to failure of zona block to polyspermyUpdated:01/14/19 Errors in Fertilization (cont.)•Polygyny»Multiple maternal pronuclei + 1 paternal pronuclei»Artificially created only•Suppress extrusion of the PBII•Androgenote»Union of 2 paternal pronuclei»Artificially created only•From pronuclear exchangeUpdated:01/14/19 Errors in Fertilization (cont.)•Gynogenote»Union of 2 maternal pronuclei»Artificially created•Induced oocyte activation and supression of PBII extrusion•Parthenogenesis»Activation of the oocyte without a sperm»Embryo is either haploid or gynogenesis occurs to form diploid•Platties - sperm activates but then gynogenesis occurs and sperm extruded from embryoUpdated:01/14/19 Oocyte Development and FertilizationMPFMPFMPFMPFPrimary OocyteGV-IntactGVBD (8 hr)Metaphase IPB-1Secondary OocyteMetaphase II (21 hr)Ovulation(29 hr)LH Surge (0 hr)Updated:01/14/19 Zona PellucidaPerivitellineSpaceOocyteCa2+Sperm Penetration of theZona PellucidaandFusion with the Oocyte(30 hr)Updated:01/14/19 Embryo Development in the Bovine2 cell (62 hr, day 2)4 cell (75 hr, day 3)8 cell (90 hr, day 3)16 cell (120 hr, day 4)32 cellMorula(day 5-6)Zygote(34 hr, day 1)TightMorula(day 6-7)Early Blastocyst(day 7-8)Blastocyst (day 7-9)ExpandedBlastocyst(day 8-10)HatchedBlastocyst(day 9-11)CompactionCompactionBlastocoelBlastocoelInner CellMassInner CellMassTrophectodermTrophectodermUpdated:01/14/19 Fertilization to CleavagePolar BodyZona PellucidaPronucleiPerivitelline SpaceZygoteZygoteBlastomereUpdated:01/14/19 Fertilization to Cleavage•Imprinting•Maternal Gene Control•Long Cell Cycle•Imprinting•Maternal Gene Control•Long Cell CycleUpdated:01/14/19 ImprintingEgg PronucleusEgg PronucleusSperm PronucleusSperm PronucleusControlsAndrogenoteAndrogenoteGynogenoteGynogenoteUpdated:01/14/19 ImprintingAndrogenote GynogenoteControls•No Inner Cell Mass•Normal Placenta•Fails during embryo development•Normal Fetus•Small Placenta•Fails Midpregnancy•Normal Fetus•Normal Placenta•Normal PregnancyMaternal and Paternal Genomes Are Expressed Differently in the Embryo and FetusMaternal and Paternal Genomes Are Expressed Differently in the Embryo and FetusUpdated:01/14/19 Gene Control of DevelopmentOocyteGrowthLHSurgeFertilization Cleavage•Transciption•Translation•Transcription•Translation•Post-Translation•Translation•Post-Translation•No transcription•Translation•Post-TranslationMaternal Gene ControlMaternal Gene ControlEmbryonicGeneControlEmbryonicGeneControlUpdated:01/14/19 Fertilization to CleavageMaternal Gene ControlMaternal Gene ControlUpdated:01/14/19 Fertilization to Cleavage•Long Cell Cycle»Penetration to Cleavage•Long Cell Cycle»Penetration to Cleavage32 hour(Bovine)32 hour(Bovine)Updated:01/14/19 Precompaction Cleavage•Cell size decreases •Cell cycle•Embryonic gene control•Asynchrony of cell divisions•Movement into Uterus •Early pregnancy factor•Cell size decreases •Cell cycle•Embryonic gene control•Asynchrony of cell divisions•Movement into Uterus •Early pregnancy factorUpdated:01/14/19 Precompaction Cleavage•Cell size decreases•Cell cycle•Asynchrony of cell divisions•Embryonic gene control•Movement into Uterus •Early pregnancy factor•Cell size decreases•Cell cycle•Asynchrony of cell divisions•Embryonic gene control•Movement into Uterus •Early pregnancy factorUpdated:01/14/19 Precompaction Cleavage•Cell size decreases•Cell cycle•Embryonic gene control•Asynchrony of cell divisions•Movement into Uterus •Early pregnancy factor•Cell size decreases•Cell cycle•Embryonic gene control•Asynchrony of cell divisions•Movement into Uterus •Early pregnancy factor13 hours13 hours15 hours15 hours30 hours30 hours32 hours32 hoursUpdated:01/14/19 G1SG2 + MCell Cycle Lengths16 hr16 hr8 hr8 hr8 hr8 hr8 hr8 hr2 hr2 hr<1 hr<1 hrTotal = 32 hours Total = 13 hours1st Cell Cycle(zygote 2 cell)2nd Cell Cycle(2 cell 4 cell)Updated:01/14/19 Precompaction Cleavage•Cell size decreases•Cell cycle•Embryonic gene control•Asynchrony of cell divisions•Movement into Uterus •Early pregnancy factor•Cell size decreases•Cell cycle•Embryonic gene control•Asynchrony of cell divisions•Movement into Uterus •Early pregnancy factor13 hours13 hours15 hours15 hours30 hours30 hours32 hours32 hoursShort G1 and G2Short G1 and G2Short G1 and G2Short G1 and G2Updated:01/14/19 Precompaction Cleavage•Cell size decreases •Cell cycle•Asynchrony of cell divisions•Embryonic gene control•Movement into Uterus •Early pregnancy factor•Cell size decreases •Cell cycle•Asynchrony of cell divisions•Embryonic gene control•Movement into Uterus •Early pregnancy factorFaster dividingblastomeres go to center of embryoFaster dividingblastomeres go to center of embryoUpdated:01/14/19 Asynchronous Cleavage - Inside Outside
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