The effects of colchicine on the ultrastructure of dividing plant cells, xylem wall differentiation and distribution of cytoplasmic microtubules

[摘要] Toclarifythepossiblefunctionsofmicrotubulesinplantcells,activelygrowingtissuesofthewheatseedlingweretreatedwithcolchicine.Individingcells,microtubulesdisappearedfromthespindle,nomatterwhatstageinthemitoticcyclehadbeenreachedpriortocolchicineapplication.Invasionofthespindlebymicrotubulesandendoplasmicreticulumatmetaphasewasnotevident,andnometaphaseplateconfigurationwasfound.Anaphasechromosomesbecomescatteredthroughoutthecytoplasm.Attelophase,cellplateformationdidnotoccur;binucleatecells,dumbbell-shapednuclei,andincompleteolderwallsbetweencellsweresometimesseen.Inxylemcells,mostwallmicrotubulesdisappearedinyoungercells,thosefewremainingbeingfoundininvaginationsofthewall.Withslightlyoldercells,wallthickeningswereformed,buttheseentirelylackedanyregularityinsizeordistributionalongthewall.Thefewmicrotubulespresentweregenerallyfoundbesidethethickenings.Laterstillinthedevelopmentalsequence,massiveirregularwalldepositionoccurredwhichresultedintheformationofgrosslymalformedthickenings;thebasicfibrillartextureofthewallappearedunchanged,butnomicrotubuleswerepresentintheusualpositionabovesuchthickenings.Thecytoplasmofalltreatedcellsappearedgenerallynormal,exceptforthelossofmicrotubulesandalsooccasionallysomechangesinthepatternsofpolysomes;ribosomes,normallypresentascomplexspiralpatterns,wereoftenspreadevenlyoverthesurfaceoftheendoplasmicreticulum.Theresultsarediscussedintermsofthepossiblerolesofmicrotubulesascytoplasmicagentsinvolvedinmicrofibrilsynthesis,walldifferentiation,andmorphogenesis.

[学科分类] 生物科学（综合）