Signification de l'“atrophie” des surrénales foetales du rat provoquée par l'hypophysectomie (décapitation)

[摘要] Ithaslongbeenrecognizedthatindecapitatedfetusestheearlierthepituitaryisremovedthegreateristhereductioninfetaladrenalcortexobservedatterm.Ininterpretingsucharesulttwokindsoffactorsshouldbeconsidered.(1)alongerperiodofpituitarydeprivationmightpermitamorepronouncedinvolutionoftheadrenals;(2)sincetheadrenalsareallthemoreembryonicwhenthepituitaryisremovedearlier,conspicuousdifferencescouldbeexpectedtobefoundattermiftheadrenalsjustmoreorlessretainedtheirinitialcondition.Growthanddifferentiationoftheadrenalswasstudiedafterdecapitationofratfetusesatvariousstages.Infetusesdecapitatedonday1612,theweightoftheadrenalsincreasesuntilday2112,butmuchlessthanincontrols(Fig.2).Inthosedecapitatedat1712daysofage,anincreaseinadrenalweightoccursthenextday,andinthosedecapitatedat1812daysaslightdecreaseisnoticed.Inthethreegroupsofanimalstheadrenalsattainonday2112aweightcorrespondingtothevalueforanormal18-day-oldfetus.Infetusesdecapitatedonday1912theweightoftheadrenalsdecreasesonlyslightly;itessentiallymaintainsthegainacquiredduringthepreviousday.ResultsareexpressedasrelativeweightofadrenalstobodyweightinFig.3oraspercentageinadrenalweightincreaseorlossinFig.4.Thecellsoftheadrenalcortexundergoanactualinvolution,characterizedbyavolumedecrease(Fig.6).Thisdecreaseincellularsizecanbecompensatedforbycellproliferationtosuchanextentthattheweightoftheglandstillincreases(decapitationat1712days).Thewellknown“atrophy”oftheadrenalsindecapitatedratfetusesresultsactuallyfromaspecialmodeofdevelopmentintheabsenceofthepituitary.Theseobservationshavebeencorrelatedwiththeeffectsofthefetaladrenalsonhepaticglycogendeposition.

[学科分类] 生物科学（综合）