Ixesha le-embryogenesis, oko kukuthi, xa umbungu ukhula kwaye ukhula, uhlala ukususela ngowokuqala ukuya kwi-iveki ye-11 ukuya kwe-12 yokukhulelwa. Emva kolu xesha, imbungu isele ibizwa ngokuba ngumntwana. Kule meko, usuku lokuqala lokuhamba kwindoda kuthathwa njengento yokuqala.
Uphuhliso lobomi obutsha luqala ngomzuzwana xa u-ovum wesifazane utyalwa. Xa i-spermatozoon kunye ne-ovum zidibanisa, i-zygote isungulwa, eqala ukuhlula kwiiyure ezingama-26 ukuya ku-30 kwaye yenza i-embro-multicellular embryo, ubukhulu bayo, njengoko bathethayo, bonyuka ngokunyuka kunye nemida.
Ukuba ezinsukwini ezine zokuqala kubakho i-embryo inokulinganisa malunga ne-0.14 mm, ke ngosuku lwesithandathu lufikelela kwi-0.2 mm, kwaye ekupheleni kwe-six-0.3 mm.
Ngomhla wesi-7-8, i-embryo ifakwa kwisalathisi se-uterine.
Ngosuku lwe-12 lophuhliso, ubukhulu bombindi sele sele bu-2 mm.
Sitshintsha ubukhulu bombindi ngeveki yokukhulelwa
- kwiveki yesi-3 yokuphuhliswa kwembungu, oko kukuthi, kwiveki yesi-5 yokukhulelwa, i-ectoderm kwindawo yesiganeko esizayo somntwana yenza i-groove. Emva koko iingcambu zalo zivaliwe kwaye ityhubhu ye-neural iyakhiwa - i-future woror and brain. Ekupheleni kweliveki, imbungu iyafikelela kuma-4 mm;
- Ngeveki yesine, inkqubo ye-nervous central ivela kwiphubhu ye-neural - i-dorsal kunye nengqondo. Intliziyo yenza isenzo sokuqala saso. Ukubonakala kweemilenze, izandla, amehlo kunye nezitho zangaphakathi, ziqala ukugeleza ngegazi kwimithambo yegazi;
- kwiiveki ezi-5 ukuya ku-6, intloko kunye neembonakalo zobuso bombungu zenziwa. Ubude bayo buyi-1 cm
- ngeveki ezi-7 izitho zize zize ziqale ukwenza imiphunga. Intliziyo eyenziwe ngokupheleleyo. Ubukhulu bombindi ngu 1.5 cm;
- Kwiiveki ezi-8 zonke izitho ezibalulekileyo zenziwa ngokukhawuleza. Ubukhulu bombindi bu malunga no-2 cm;
- kwiiveki ezili-9 ezibonakalayo ezibonakalayo, iimpumlo, iinkophe, umlomo, amehlo. Ukuphakama kwengane malunga ne-3 cm kwaye iyaqhubeka ikhula ngokukhawuleza;
- kwiiveki ezi-10, oko kukuthi, kwiiveki ezili-12 zokukhulelwa, isakhiwo salo mzimba sichaphazela ngokufanelekileyo kumntu. Izitho zomzimba zandiswe. Igazi lomntwana lizuza iqela layo. Ubungakanani bembungu, obuya kuba yimeko yobungqina, buya kufinyelela kwi-7 cm.
Ukunyuka kobukhulu bombindi kunokulandelwa ngokwetafile apha ngezantsi.