Effects of the Brachyury (T) mutation on morphogenetic movement in the mouse embryo

[摘要] TTembryoshavebeenfirstdistinguishableat8dayspostcoitumbytheirgrossmorphologicalabnormalities.Byquantitativemorphometryofhistologicalsections,anomaliesinthehomozygoteswereexpressednumerically.At8daysp.c.,morphologicallyidentifiableT-homozygoteshadanincreasednumberofectodermalandareducednumberofmesodermalcellscomparedtothewildtype.At7daysp.c.,embryoswithalowmesoderm/ectodermratiowerefoundonlyinlittersofT+×T+matingsattheexpectedfrequency.At6daysp.c.,one-fourthoftheembryosinT+×T+littersshowedadelayinthetransitionfromcuboidaltosquamousendoderm.Nosuchembryoswerefoundinthe+/+×+/+matings.In6-,7-,and8-daymutantembryos,cellsproliferatedatstatisticallynormalrates.Therefore,itmaybesaidthatadvancedmorphologicalirregularitiesof8-dayhomozygotescannotbeaccountedforbyanomaliesincellproliferation.Whenthetotalcellnumberwas5×104/embryo(8days),asuddenchangewasobservedintheregionaldistributionofmesodermalandectodermalcellsalongtheanteroposterioraxisofTTembryos.Sincenoregionaldifferenceinthecellcycletimewasobserved,theseabnormalitiesmaybestbeexplainedbyanomaliesincellmigration.TheseresultsstronglysuggestabnormalmorphologyofTTmutantsresultingfromdefectsinmorphogeneticmovement.

[学科分类] 生物科学（综合）