The influence of various cell kinetic conditions on functional differentiation in the small intestine of the rat: A study of enzymes bound to subcellular organelles

[摘要] Theprocessofcellmaturationandcellageingofabsorptiveepithelialcellswasinvestigatedinnormalratduodenum.Thedevelopmentofanumberofenzymesboundtosubcellularorganelleswasstudiedbyusingmicrochemicalanalysesonvariouscellcompartmentsdissectedfromcryptsandvillifromfreeze-driedcryostatsections.Thedevelopmentoftheultrastructuralfeaturesoftheabsorptiveepitheliumwasinvestigatedbyelectronmicroscopyofvariouscellpositionsalongthewholelengthofthecryptandthebaseofthevillus.Thedataobtainedwererelatedtocellpositionalongthecryptandvillusandtocellageduringmigrationfromthebottomofthecrypttothetipofthevillus.Theinfluenceofchangesinthelife-spanofthecellsandofincreasingproliferativeactivitywasstudiedbycomparingnormalratduodenumwiththatfromgermfreeratsandratsrecoveringfromlowradiationdoses(72hrafter400R).Ourdatashowthatthespecificactivityofnonspecificesterasesmainlylocalizedintheendoplasmicreticulumincreaseswhenthecellsmigratealongtheupperhalfofthecryptandthebasalpartofthevillus.Activityofalkalinephosphatase,measuredasamarkerforthemicrovilli,isabsentinthecrypt,butincreaseslinearlyfromthebaseofthevillustothetip.Thelongerlife-spanofvilluscellsingermfreeanimalsdoesnotresultinahigheractivityoftheseenzymesthaninnormalanimals.Anincreasedproliferativeactivityinthecrypt,aspresent72hrafterX-irradiation,isaccompaniedbyadecreasedactivityofbothenzymesbutthepatternofactivityduringcellmigrationremainsthesame.Thespecificactivityofenzymesboundtomitochondriaorlysosomes(monoamineoxidaseandβ-N-acetylglucosaminidase)arenotaffectedbychangingcryptcellkinetics.ElectrophoreticanalysesofisolatedcellcompartmentsshowedthattheincreaseduringnormaldifferentiationorthedecreaseafterX-irradiationofesteraseactivityisduetochangesinoverallactivity,nottotheappearanceordisappearanceofspecificisoenzymes.Electronmicroscopyshowedthatinthenormalintestinethereisagradualdevelopmentofultrastructuralfeaturesduringmigrationofthecellalongthecryptwhilethemostdrasticchangesincellstructureoccuratthemomentthecellentersthevillus.Contrarytoourexpectation,theultrastructuraldevelopmentwasnotinfluencedbyincreasedproliferativeactivityinthecrypt72hrafterirradiation,andhencethedecreaseinenzymeactivityfoundcannotberelatedtochangesinultrastructure.

[学科分类] 生物科学（综合）