Njengomthetho, kunzima ukukhomba ukuthi iqanda lenziwa yini, ngakho-ke ukuqala kokukhulelwa kuqala ukubala kusukela ngosuku lokuqala komjikelezo wokugcina esikhathini.
Umanyolo
Kusukela manje kuqala ukwakheka nokuvuthwa okulandelayo kweqanda. Ukukhulelwa kwakhe kwenzeka phakathi kwamasonto amabili kuya kwamabili.
Ngaphambi kokuhlangana kwamaseli wesilisa nowesifazane, kuzothatha amahora amathathu kuya kwangu-6. I-spermatozoa eningi, ehamba emaqanda, ihlangana nezindlela eziningi ezithintekayo, ngenxa yalokho, i-spermatozoa enamandla kunayo yonke ifinyelela emgomweni. Kodwa kuphela oyedwa kuzoba yingxenye yenqubo yokukhulelwa.
Lapho i-spermatozoon inqoba isembatho seqanda, khona-ke umzimba wesifazane uqala ukuvuselela umsebenzi wawo, okuzobe sekuhloswe ngawo ukugcina ukukhulelwa.
Ngenkathi yokukhulelwa, iseli elisha elinalo i-genetic code, elizocacisa ubulili bomntwana, ukuma kwendlebe, umbala wamehlo kanye nezinye izici, lwakhiwa kusuka kumaseli omzali ababili, ngalinye libe nesigamu seqoqo lama-chromosomes ngayinye.
Ngosuku lwesine kuya kwelesishiyagalolunye, iqanda elikhulelwe lifinyelela esibelethweni. Ngalesi sikhathi, sesivele isakhula ibe umbungu oqukethe amangqamuzana angaba ngu-100.
Ukufakelwa emgodini wesibeletho kwenzeka ekuqaleni kweviki lesithathu. Emva kwalokhu ukukhulelwa kuqediwe. Ukuhamba kwesibeletho nokunamathiselwe kwodonga lwaso kuyisigaba esiyingozi kakhulu sokuthuthukiswa komntwana ekuqaleni kwenyanga.
Ukubunjwa kwe-fetus
Ngenyanga yokuqala emva kokuphela kwenqubo yokufakelwa, ukubunjwa kokubeletha okusebenzayo kuqala. I-chorion iqala - i-placenta yesikhathi esizayo, i-amnion-isandulela sesibindi sesisu nesibindi somzimba. Ukuthuthukiswa kwe-fetus ngenyanga yokuqala yokukhulelwa kuqala ngokubunjwa kwamapheshana amathathu okumbumbulu. Ngamunye wabo umele umbungu wezitho ezihlukene nezicubu.
- Iqabunga elingaphandle le- embryonic liyisigqila sesimiso sezinzwa, amazinyo, isikhumba, izindlebe, i-epithelium yamehlo, impumulo, izipikili nezinwele.
- Iqabunga eliphakathi kwamagciwane liyisisekelo sesisindo (imisipha yamathambo, izitho zangaphakathi, umgogodla, i-cartilage, izitsha, igazi, i-lymph, izilonda zobulili).
- Iqabunga eliphakathi kwamabrionic liyisisekelo sokwakheka kwekhanda elimangalisa le-system yokuphefumula, izitho zomuthi wamathumbu, isibindi nama-pancreas.
Ekupheleni kwenyanga eyodwa yokukhulelwa, i-fetus (embryo) isivele inebude buka-1 mm (umbungu ubonakala emehlweni). Kukhona ibhukumaka ye-chord - umgogodla wesikhathi esizayo. Kukhona ibhukumaka yenhliziyo nokubukeka kwemithambo yegazi yokuqala.