In the mesoderm txheej yog cov yolk sac blood islands blood islands Blood islands yog structures nyob ib ncig ntawm lub embryo tsim uas ua rau ntau qhov sib txawv ntawm cov hlab ntsha.. Ntshav cov Islands tuaj tshwm rau sab nraud rau kev loj hlob embryo nyob rau hauv lub plab vesicle, allantois, txuas stalk thiab chorion. https://en.wikipedia.org › wiki › Blood_islands
Ntshav Islands - Wikipedia
uas cim qhov chaw ntawm thawj embryonic hematopoiesis thiab vasculogenesis. Los ntawm 8 hnub ntawm txoj kev loj hlob, lub vitelline ncig yog tsim, txuas lub yolksac thiab lub embryonic ncig.
Dab tsi yog qhov ua haujlwm ntawm 4 extraembryonic membranes?
Muaj plaub qhov ntxiv-embryonic daim nyias nyias feem ntau pom hauv VERTEBRATES, xws li REPTILES; HUAB TAIS; thiab MAMMALS. Lawv yog YOLK SAC, ALLANTOIS, AMNION, thiab CHORION. Cov membranes no muab kev tiv thaiv thiab txhais tau tias thauj cov as-ham thiab pov tseg.
Yuav ua li cas hauv qab no yog thawj cov kab mob extraembryonic tshwm sim?
Yolk Sac: Thawj cov kab mob extraembryonic rau daim ntawv yog lub hnab yolk. Raws li lub cev folds undercut lub embryo, lub splanchnopleure (splanchnic mesoderm + endoderm) nqaim heev los tsim lub yolk stalk: ib qho kev sib txuas ntawm lub plab thiab lub qe. Lub hnab yolk tsim raws li lub splanchnopleure nyob ib ncig ntawm lub yolk.
Ua cas extraembryonicmembrane ua qhov chaw ntawm cov ntshav tsim thaum ntxov?
Raws li lub limtiam zuj zus, cov xov tooj ntawm tes sab hauv tshem tawm nws tus kheej los ntawm trophoblast thiab dhau los ua cov embryonic disk, thiab ob daim ntawv extraembryonic daim nyias nyias (Fig. 8.4a). Lub yolksac yog thawj qhov chaw ntawm cov qe ntshav tsim. Lub amniotic kab noj hniav nyob ib ncig ntawm lub embryo (thiab tom qab ntawd tus me nyuam hauv plab) thaum nws loj tuaj.
Dab tsi yog cov kab mob txheej txheem ntawm plaub lub extraembryonic membrane?
Txhua tus amniotes muaj plaub yam hauv qab no: cov amnion, chorion, yolk sac, thiab allantois (Fig. 1C). Zoo li cov ntaub so ntswg intraembryonic, cov ntaub so ntswg extraembryonic yog tsim los ntawm cov hlwb uas sawv cev rau peb txheej kab mob: ectoderm, mesoderm, thiab endoderm.
