BILD 2: Multicellular LifeLECTURE #25Website: http://www.biology.ucsd.edu/classes/bild2.WI11.1Instructor: Darwin K. Berg ([email protected])ANNOUNCEMENTS:1) Final Review Session: Wed, Mar 16, 5-8 pm, 3500 Pacific Hall.Building entrance code that day: 701181.2) Final Exam: Fri, Mar 18, 8-10:50 am, WLH 2001.3) Relevant Material for the Final Exam:a) A third devoted exclusively to the last third of the course.b) The remaining two-thirds: comprehensive (entire course).Fig. 47-3: Acrosomal and Cortical Reactions during Sea Urchin FertilizationBasal body(centriole)SpermheadSperm-bindingreceptorsAcrosomeJelly coatVitelline layerEgg plasmamembraneHydrolytic enzymesAcrosomalprocessActinfilamentSpermnucleusSperm plasmamembraneFusedplasmamembranesFertilizationenvelopeCorticalgranulePerivitellinespaceEGG CYTOPLASM1. Sperm contacts eggjelly coat, triggeringexocytosis of spermacrosome2. Enzymes from acrosome makehole in jelly coat. Actin filamentsform from the acrosome/sperm-headand penetrate the jelly coat. Proteinson the acrosome bind to receptorson the egg membrane3. Fusion triggers depolarizationof the membrane which acts asfast block to polyspermy.4. Cortical granules in egg fusewith the membrane. The secretedcontents clip off the sperm-binding receptors & causeferilization envelope to form; actsas slow block to polyspermy.5. Entry ofsperm nucleusFig. 47-5: Fertilization in MammalsFollicle cellZona pellucidaCorticalgranulesSpermnucleusSpermbasal bodyFig. 47-6: Early Cleavage in an Echinoderm Embryo(a) Fertilized egg (b) Four-cell stage (c) Early blastula (d) Later blastulaFig. 47-9: Gastrulation in a Sea Urchin EmbryoFuture ectodermKeyFuture endodermDigestive tube (endoderm)MouthEctodermMesenchyme(mesodermforms futureskeleton)Anus (from blastopore)Future mesodermBlastocoelArchenteronBlastoporeBlastoporeMesenchymecellsBlastocoelBlastocoelMesenchymecellsArchenteronVegetalplateVegetalpoleAnimalpoleFilopodiapullingarchenterontip50 mFig. 47-8: Cleavage in a Frog EmbryoBlastula(crosssection)BlastocoelAnimal pole4-cellstageforming2-cellstageformingZygote8-cellstageVegetalpole0.25 mm0.25 mmFuture ectodermKeyFuture endodermFuture mesodermSURFACE VIEWAnimal poleVegetal poleEarlygastrulaBlastoporeBlastocoelDorsal lipof blasto-poreCROSS SECTIONDorsal lipof blastoporeLategastrulaBlastocoelshrinkingArchenteronBlastocoelremnantArchenteronBlastoporeBlastoporeYolk plugEctodermMesodermEndodermFig. 47-10:Gastrulation ina Frog EmbryoFig. 47-12: Early Organogenesis in a Frog EmbryoNeural foldsTail budNeural tube(b) Neural tube formationNeuralfoldNeural plateNeuralfoldNeural plateNeural crestcellsNeural crestcellsOuter layerof ectodermMesodermNotochordArchenteronEctodermEndoderm(a) Neural plate formation(c) SomitesNeural tubeCoelomNotochord1 mm1 mmSEMSomiteNeural crestcellsArchenteron(digestivecavity)SomitesEyeFig. 47-14: Adult Derivatives on the Three Embryonic Germ Layers in VertebratesECTODERM MESODERM ENDODERMEpidermis of skin and itsderivatives (including sweatglands, hair follicles)Epithelial lining of mouthand anusCornea and lens of eyeNervous systemSensory receptors inepidermisAdrenal medullaTooth enamelEpithelium of pineal andpituitary glandsNotochordSkeletal systemMuscular systemMuscular layer ofstomach and intestineExcretory systemCirculatory and lymphaticsystemsReproductive system(except germ cells)Dermis of skinLining of body cavityAdrenal cortexEpithelial lining ofdigestive tractEpithelial lining ofrespiratory systemLining of urethra, urinarybladder, and reproductivesystemLiverPancreasThymusThyroid and parathyroidglandsFig. 47-11: Gastrulation in a Chick EmbryoEndodermFutureectodermMigratingcells(mesoderm)HypoblastDorsalFertilized eggBlastocoelYOLKAnteriorRightVentralPosteriorLeftEpiblastPrimitive streakEmbryoYolkPrimitivestreakFig. 47-13: Organogenesis in a Chick EmbryoEndoderm(a) Early organogenesisNeural tubeCoelomNotochordThese layersform extraembryonicmembranesYOLKHeartEyeNeural tubeSomiteArchenteronMesodermEctodermLateral foldYolk stalkYolk sac(b) Late
View Full Document
Unlocking...