Esi sigaba sokuqala senkqubo yokuzala sinokufutshane
I-zygote ibumbano lentsholongwane yesilwane kunye neliqanda leqanda. Eyaziwa nangokuthi i-ovum ekhulile, i-zygote iqala njengeeselinye enye kodwa ihlula ngokukhawuleza kwiintsuku ezilandelayo emva kokuchumisa. Emva kweeveki ezimbini zee-cell division, i-zygote ekugqibeleni iyaba ngumbungu. Ukuba oku kuhamba kakuhle, i-embryo iba ngumntwana.
Zygotes Ifomu?
Ukuze kwenziwe ukuveliswa, enye inqindi yeselingi kufuneka ingene ngaphakathi kwinqaba.
Kwiimeko ezininzi, iseli enye yeqanda ikhutshwe ngexesha le-ovulation yonyaka wokuzala umntwana. Ngokuqhelekileyo, iinzame zemizamo yesininzi ukungena kweli seli elinye leqanda. Xa isityalo esisodwa siphule ngaphaya komhlaba, ukuguqulwa kweekhemikhali kummandla weqanda kukuthintela olunye uhlobo lwesidoda ukungena.
Le nkqubo idla ngokuqhubekayo ngexesha lokwabelana ngesondo, nangona uncedo olusisuncedo lwezochumiso lunokunokwenzeka. I-intrauterine insemination (IUI) kunye ne-vitro fertilization (IVF) zibini eziqhelekileyo zisetyenziselwa ubuchule bokuzala.
Ngethuba le-IUI, i-semen ifakwe kwisisu ngokusebenzisa i-catheter ukuze ukuchumisa kwenzeke ngaphakathi komzimba wesifazane. Kwi-IVF, amaqanda asuswa kuma-ovari kwaye atyulelwe kwibhobhu. I-zygote isetyenziswe kwisibeleko.
Yintoni eyenzekayo emva koManyolo?
I-zygote ihlula kwinkqubo eyaziwa ngokuba yi-mitosis, apho iseli ngalinye liphindwe kabini ngokuhlula kwiiseli ezimbini.
Esi sigaba seveki ezimbini siyaziwa njengexesha lokukhula kwenkqubela kwaye lihlanganisa ixesha lokukhulelwa ekumiselweni kombungu kwisibeleko.
Kwiimeko ezininzi, iseli nganye yesini kunye nesetyhini iqukethe i-chromosomes ezingama-23. Inambuzane yeselwane iqulethe ulwazi lofuzo kubazali ngelixa iseli leqanda liqulethe ulwazi lomfuzo kumama.
Ngenxa yokuba iseli nganye iqulethe isiqingatha sezinto eziphathekayo zofuzo, iseli nganye isaziwa njengeselula ye haploid.
Xa ezi zimbini ze-haploid zidibanisa, zenza iseli enye ye-diploid equle i-chromosomes ezingama-46. I-zygote ize ihambe phantsi kwiphubhu ye-fallopian ukuya kwisibeleko apho kufuneka ifakwe kwisitya ukuze ifumane ukutya okufuneka ikhule kwaye iphile.
Ukuba le nkqubo ihamba kakuhle, i-zygote iya kuqhubeka ikhula ize ifinyelele kwisigaba esilandelayo sokuphuhliswa kokubeletha.
Isigaba seZygote siphelile ixesha elingakanani?
Ixesha le-zygote lifutshane, lihlala ixesha eli-4. Ngomhla wesihlanu, ubuninzi beeseli baziwa ngokuba yi-blastocyst. Ixesha leentsholongwane liya kuhlala lilishumi elinesine, emva koko i-embryonic period iza kuqala.
Ixesha lesibini lentuthuko lihlala kwiiveki ezimbini emva kokukhulelwa ngeveki yesibhozo, ngelixesha apho inyama iyaziwa njenge-embryo. Ngeveki yesithoba, emva kwexesha lokukhulelwa, ixesha lokutshatyalala liqala. Ukususela ngeli nqanaba de kube sekuzalweni, umzimba ubizwa ngokuba ngumntwana.
Akunjalo onke ama-zygotes akwenza kwisigaba esilandelayo sophuhliso lokubeletha, nangona kunjalo. Abaphandi baqikelela ukuba iipesenti ezingama-30 ukuya kwezingama-70 yazo zonke iimpawu eziqhelekileyo zenzeke phambi okanye ngexesha lokumiswa.
> Imithombo:
> Niakan, K., et al "Ukuphuhliswa komzimba kwangaphambili." KuKhula ka-2012