Glycosaminoglycan synthesis in rat embryos during the formation of the primary mesenchyme and neural folds☆

[摘要] Glycosaminoglycan(GAG)synthesiswasstudiedinexplantedratembryosonDays7(preprimitivestreak),8(primitivestreak),9(0–4somites),and10(6–10somites)bylabelingwith[3H]glucosamineor35SO4.SpecificGAGwereidentifiedbyelectrophoresisandsensitivitytodegradationbyspecificenzymesortreatments.Bythesecriteria,thelabeledGAGwereidentifiedaseitherhyaluronicacid,chondroitinorchondroitinsulfates,orheparansulfate.IntheDay7embryoproper,glucosaminewasequallyincorporatedintohyaluronate,chondroitinorchondroitinsulfate,andheparansulfate,whereas,byDay9,about83%oftheglucosamine-labeledGAGwashyaluronate,5%inchondroitinorchondroitinsulfateand11%inheparansulfate.Whenexpressedasglucosaminecountsincorporatedpermicrogramofprotein,thisrepresentsa16-foldincreaseinhyaluronateduringtheformationoftheprimarymesenchyme.SimilarGAGweremadebyboththeanteriorandposteriorhalvesoftheembryo,buttheanteriorhalfincorporated1.75timesasmuchglucosamineintoisolatedGAGasdidtheposteriorhalf.Intheextraembryonictissues,about24%ofthelabelwasinhyaluronicacid,44%inchondroitinorchondroitinsulfate,and35%inheparansulfate.Therewerenostage-relatedchangesinthepatternsoflabelingintheextraembryonictissues.Itisshownthatincreasedhyaluronicacidsynthesisintheembryoiscorrelatedwiththeformationoftheprimarymesenchymeanditsassociatedcellfreespacesandtheneuralfolds.

[学科分类] 生物科学（综合）