Ukuthuthukiswa kombungu wesintu?
Isikhathi sonke sokuthuthukiswa komzimba womzimba womuntu ngokuvamile sihlukaniswe ngezigaba ezine eziyinhloko. Masikhulume ngomunye wabo ngokwehlukana.
Isigaba sokuqala yisikhathi esifushane futhi sibonakala ngokuhlanganiswa kwama-germ cells, okuholela ekwakheni i- zygote.
Ngakho-ke, ekupheleni kosuku lokuqala kusukela ngesikhathi sokukhulelwa kwesisini selesilili besifazane, isigaba sesibili sokuthuthukiswa siqala - ukuchoboza. Le nqubo iqala ngokuqondile emathunjini asebusuku futhi ihlala cishe ngezinsuku ezingu-3-4. Phakathi nalesi sikhathi, umbungu ozayo uzoqhubeka ufike emgodini wesibindi. Kumele kuqashelwe ukuthi ukuhlukaniswa komuntu kuqediwe futhi kungenasisekelo, okwenza kube nokwakhiwa kwe-blastula - isethi sezinto ezakhiwe ngezakhi ezithile, i-blastomeres.
Isigaba sesithathu , ukugcoba, kubonakala ngokuhlukaniswa okuqhubekayo, lapho kuhlanganiswa khona i-gastrula. Kule-gastrulation kunezinqubo ezimbili: ukwakheka kwe-embrym-two-layered, equkethe i-ectoderm ne-endoderm; ngokuthuthukiswa okuqhubekayo, kwakhiwa ama-embryonic leaf - mesoderm amathathu. Ukugcoba ngokwayo kubonakala ngukuthi okuthiwa ukungena ngaphakathi, lapho amangqamuzana e-blastula atholakala kwelinye lamapulangwe afakwa ngaphakathi. Ngenxa yalokho, kuhlanganiswa isikhala, okuthiwa i-gastrocole.
Isigaba sesine sokuthuthukiswa kwamabriyoni, ngokusho kwetafula elingezansi, ukuhlukaniswa kwezingxenye eziyinhloko zezitho nezicubu (organogenesis), kanye nokuthuthukiswa kwazo okuqhubekayo.
Ukubunjwa kwezakhiwo ze-axial kanjani emzimbeni womuntu?
Njengoba sekuyaziwa, cishe ngosuku lwesikhombisa kusukela ngesikhathi sokukhulelwa, umbungu uqala ukufakwa ungqimba lwamanzi esibelethweni. Lokhu kungenxa yokukhululwa kwezingxenye ze-enzymatic. Le nqubo ibizwa ngokuthi ukufakelwa. Kungenxa yakhe ukuqala kokubeletha - isikhathi sokukhulelwa. Phela, hhayi njalo emva kokuba umanyolo ukhulelwe.
Ngemuva kokufakelwa emgqeni wesibeletho, ingqimba yangaphandle ye-embryo iqala ukuqala kwe- gonadotropin ye- hormone - chorionic. Ngokuqondile, ukuhlushwa kwakhe, ukukhuphuka, kukuvumela ukwazi owesifazane ukuthi maduzane abe umama.
Ngeviki lesi-2, ukuxhumana kuqiniswa phakathi kwe-villi ye-fetus kanye nezitsha zomzimba womama. Ngenxa yalokho, ukunikezwa kwemvelo encane kuqala kancane kancane kwenziwe ngegazi lomama. Inqubo yokwakheka kwezakhiwo ezibalulekile njengoba i-placenta ne-umbilical cord iqala.
Ngezinsuku ezingaba ngu-21, umbungu usuvele usungula inhliziyo, eqala ukuqala ukuphikisana kwayo kokuqala.
Ngeviki le-4 lokubeletha, lapho uhlola umbungu nge-ultrasound, kungenzeka ukuhlukanisa izigqoko zamehlo, kanye nemigqa yemilenze yawo yesikhathi esizayo namapenki. Ukubonakala kombungu kubonakala kakhulu kufana ne-auricle, okuzungezwe inani elincane le-amniotic fluid.
Ngeviki lesi-5, izakhiwo zobuso obubuso bekhanda le-embryo ziqala ukwakha: impumu nephunga eliphezulu lihlukaniswa ngokucacile.
Ngesonto le-6, i-thymus gland iyakha, okuyinto engxenyeni ebaluleke kunazo zonke ohlelweni lomzimba lomzimba.
Ngeviki lesi-7, ukwakheka kwenhliziyo emlonyeni kuyathuthuka: ukwakheka kwe-septa, imithwalo yegazi emikhulu. Ama-dile amathanga avela esibindi, izigcawu zesimiso se-endocrine zikhula.
Iviki lesishiyagalombili lenkathi yokuthuthukiswa etafuleni libhekiswe ekupheleni kwebhukimakhi yezimpawu zamalungu ombungu. Ngalesi sikhathi, ukukhula okujulile kwezitho zangaphandle kubonakala, ngenxa yalokho umbungu uba njengendoda encane. Ngesikhathi esifanayo, kungenzeka ukuhlukanisa ngokucacile izici zocansi.
Iyini ukuthuthukiswa kwe-post-embryonic?
Ukuthuthukiswa kwe-Embryonic kanye ne-postembryonic - izikhathi ezingu-2 ezihlukene ekuthuthukiseni kwanoma yimuphi umzimba. Ngaphansi kwenqubo yesibili, kuyisiko ukuqonda isikhathi sokuzalwa komuntu kuze kube sekufeni kwakhe.
Ukuthuthukiswa kwe-Postembryonic kubantu kubandakanya izikhathi ezilandelayo:
- Izingane (ngaphambi kokuba inqubo yokukhulelwa iqale).
- Ukukhula (umuntu omdala, isimo esivuthiwe).
- Inkathi yokuguga, ekupheleni kokufa.
Ngakho-ke, kulula ukuqonda ukuthi yiluphi uhlobo lwentuthuko olubizwa ngokuthi ukuthuthukiswa kwe-embryonic, futhi okuyi-postembryonic.