A ComparativeStudy of Cellular Organdíes of Morris Hepatomas1

Z.Hruban,2Y.Mochizuki,A.Slesers,andH.P.MorrisDepartmentofPathology,UniversityofChicago,Chicago,Illinois60637fZ.H.,Y.M.,A.S.J,andtheDepartmentofBiochemistry,CancerResearchUnit,HowardUniversity,Washington,D.C.20001[H.P.M.JSUMMARYThecellsoftransplantableMorrishepatomas,withtheexceptionofhepatoma3683,arepolarizedandmorphologicalchangesarefoundinthenuclei,surfaces,andcellularorgan-elles.Themostcommonnuclearchangesareinvaginationsofthecytoplasmintothenuclei,invaginationsoftheinnermembraneofthenuclearenvelope,lipidinclusions,abundantdenseinterchromatinparticlesofvarioussizes,intranucleolarmicrospherules,andmicrosegregationofnucleoli.Differencesareseeninthefrequencyandsizeofcanalicularmicrovilli.Pinocytosisispresentonallsurfacesandmicrovilliarefoundonlateralsurfaces.Dilationofintercellularspacesvaries.Microvilliatthebaseofthecellsareusuallyinfrequent,whilecoarseprotrusionsofbasalcytoplasmarecommon.Bloodvesselssupplyinghepatomashavebasementmembranes.Thespacebetweenbloodvesselsandthebaseofhepatomacellsfrequentlycontainsmultiplebasementmembranes.Hepatomacellscontain relativelymoreroundandfewerlongmitochondria whencomparedwithhepatocytes.Matricalosmiophilicgranulesarelessabundantorabsent.Fast-growinghepatomas havefewermitochondria whichshowaninfrequentspatialrelationshiptoroughcisternae.AlterationsintheGolgicomplexconsistofanumericalincreaseofdictyosomesandadecreaseofGolgivacuoles.Cytoplasmicfibrilsareabundantinfast-growinghepatomas.Theseandotheralterationsarenotspecificforneoplasia.Somechangesareprobably related tonutritional deficiencies anddegenerativeprocesses.Otheranomaliesindicatedisturbancesinorganelleformation andcompensations foralteredfunctions oforgandA­es.Theindividual geneticandenvironmentalfactorscontributingtoorganellealterationsaredifferentineachtumorand,therefore,leadtoanindependentassortmentofunitcharacters.INTRODUCTIONTransplantableMorrishepatomashavebeenwidelyusedinbiochemicalstudiesofneoplastictissues.Hepatomasoffertheadvantagethatthestudiedparameterscanbecomparedwiththoseobtainedfromnormal,regenerating,andpreneoplastic'SupportedbyUSPHSGrantCA05310fromtheNationalCancerInstitute.JResearchCareerDevelopmentAwardee.ReceivedOctober6,1971;acceptedDecember2,1971.livers.MorphologicalstudiesonMorrishepatomasare,however,infrequentandarelimitedtoafewtumorsofdistantgenerations(7,15,25).Studiesofselectedhepatomaswithextremedifferencesintheirgrowthratessuggestthatthenumbers,sizes,andalterationsoforganellesarerelatedtotheirgrowthrates(15).Recentreportsconcernedwithhistology(14),ultrastructureofmicrobodies,andcontentofmicrobodyenzymes(20,41)showthateachhepatomaremainsindividualinspiteofageneraltendencytocytoplasmicsimplificationwithincreasedgrowthrate.Thepresentstudyisconcernedwithasemiquantitativeanalysisofnuclei,cellularsurfaces,andseveralcytoplasmicorganelles.Thedatapresentedhereandinotherstudies(13,14,20)shouldenablethebiochemistandtheexperimentalchemotherapist toselectthemostsuitabletumorforaparticularstudy.MATERIALSANDMETHODSSamplesofhepatomas(Table1)andofseveralliverswereobtainedfromexsanguinatedtumor-bearingrats.Piecesgrosslyfreeofnecrosiswerefixedfor2hrat5°in1%osmiumtetroxidebufferedwiths-collidinebufferatpH7.4andembeddedinEpon(19).ThinsectionswerecutwithaPorter-Blummicrotomeandstainedwithuranylacetateandleadcitrate; selectedareaswerephotographed inaSiemens-Elmiskop 1Aelectronmicroscope. Inanotherpublication(14)thegenerationsandagesofexaminedhepatomashavebeenpreviouslyreported.RESULTSThestructuralalterationsseeninhepatomacellsareeitherquantitativedifferencesinnormalorganellesorqualitativedifferencesoftencorrespondingtoalterationsfoundinpathologicallyalteredlivercells.SemiquantitativeestimationsofcellularorganellesandparticlesarelistedinTables1to7.Additionalinformationandcommentsaregivenbelow.Nuclei.Thenuclei(Tables1and2)ofthecellsintransplantablehepatomasshowgreatervariationofsize,shape,andstructurewhencomparedwithnucleioflivercells;smallnucleiaregenerallyround,whilelargenucleihaveirregularshapesandfrequentlycontaininvaginationsofcytoplasm.Cytoplasmic invaginationsoftenhaveanarrowneck.InvaginationsoftheinnermembraneofthenuclearenvelopeAPRIL1972