Le sac ngexesha lokukhulelwa

abafazi abaninzi emva ultrasound abanomdla lo mbuzo: "Yintoni na le sac sac ngethuba lokukhulelwa, yaye yintoni na ukuba?". Thatha nomdla kuyo yonke into ngendlela enye okanye omnye inento yokwenza kwimveku - oku ke kuqhelekile. Ngoko ke namhlanje makhe sithethe yintoni na sac sac ngethuba lokukhulelwa, yaye yintoni esisebenza ngayo yenza.

Ngoko ke, phantsi sac sac oku kwakuthetha iqumrhu umbungu okwethutyana. Ngamanye amazwi, le sac sac ngethuba lokukhulelwa - namnye ngaphandle inxalenye ende umhlaza zaseprayimari, engaphandle kwimveku zoluntu kwaye inoxanduva ukuhamba kwegazi lokuqala kunye neeseli kwindawo lwegciwane sokuqala.

Formation of the sac sac ngexesha lokukhulelwa isekelwe kwiqamza endoblasticheskogo ngexesha placentation ngosuku 15-16 of kweqanda ekukhuleni.

Le sac ngexa lokukhulelwa: ukuqeshwa

Kwiiveki zokuqala zokukhulelwa (yokuqala okanye yesibini ezintathu) sac nemilinganiselo sac igqithe ubukhulu disc germinal kunye kwisisu fluid. Ukusukela leenyanga ezintathu lesithathu kwi sac sac wambumba ngokwakha uthungelwano capillary ukuba unikezele zenyukliya nakujoliso olutsha eritortsity erythropoiesis.

Ngokubanzi kokuba kuqwalaselwe ukuba abantu umbungu sac ngexesha lokukhulelwa kubaluleke kakhulu kuba nguye amalungu provisory, ababekhonza babizwa ngokuba "isibindi zaseprayimari", apho imveku ifumana iiproteni ezibalulekileyo ezifana alpha 2-microglobulin, alpha fetoprotein, njl

Emva kweentsuku 28-29 emva kokukhulelwa, iqanda sac ngexesha lokukhulelwa uba umthombo ngqo weeseli lwegciwane ukuba angene kwindawo kweendonga zayo kwawakho gonad le mveku. Njengoko ezintathu yokuqala lufikelele esiphelweni, lo sac sac kanti ukusebenza kwaye iba ukuyilwa encinane esinganyangekiyo kufuphi kwisiseko imfesane yosana.

Kubalulekile ukuba kunciphiso sac sac ngexesha lokukhulelwa ekungazange kubekho injengayo phambi kwelona xesha, ide loo mzuzu xa amalungu umbungu ziphelile. kwesisu Kungenjalo engaphephekiyo okanye izisu ephosiweyo.

Yintoni ukuyilwa egazini Huy sac?

Ekuqaleni kwiveki yesithathu iqala inkqubo hematopoiesis, nto leyo luphawulwa Ukuqhela iziqalelo isiqulatho igazi yokujikeleza weeseli eziziiprayimari hematopoietic kunye nucleoli ezinkulu nucleus kunye icytoplasm basophilic. inkqubo hematopoiesis lipheliswe ekupheleni kweveki yesine uphuhliso Umbungu kwaye koko hematopoiesis xa izihlunu osandul.

Enyanisweni, namhlanje bahlule phakathi concepts ezimbini ukuvela iiseli hematopoietic kwi umbungu. embryologists Modern kunye zegazi ngcamango athandwa kakhulu ngqo imvelaphi endothelial kwaye vnutriembrionalnogo imvelaphi mesenchymal. Sekunjalo, iingcali ngakumbi nangakumbi nithande ukubeka phambili, yaye ngenkulungwane yokugqibela ingqikelelo weseli yemfuduko ngaphandle ingxowa kwi izihlunu ezingekazalwa, nto leyo eya kuba bubungqina yemifuniselo enxulumene ukulinywa ngeembumba mouse. Xa ancedisana lwenkcubeko umbungu emva ukungabikho emfutshane evela sac iiseli sac ngokupheleleyo hematopoiesis ngaphambi ndingekho. Kwangaxeshanye, lo sac sac, nto leyo iyalinywa ngaphandle umbungu, osisityebi iiseli ezinjalo, nto leyo kwakhona uqinisekisa olwenzeka lwabo ekupheleni zemfuduko kwi ijwabu mbungu.

Noko ke, kufuneka kuqondwe ukuba umfuziselo Esalingwayo ayide ikwazi kuba sisiseko naziphi na isigqibo malunga nokusekwa hematopoiesis xa umbungu yabantu. Ezo amalinge - ithuba entsha sokuqondwa ngokucacileyo of embryogenesis kwabantu kwi zigaba yokuqala, yaye akukho ngaphezulu.