Emasontweni angu-8 okuqala okukhulelwa, umntwana ozayo ukhula ngesivinini esikhulu ... Ukwehlukana kwamangqamuzana, ukwakheka kwezitho zawo kanye nama-appendages awo, umbungu ube usuhamba esikhathini esaziwa ngokuthi i-embryogenesis. Yiziphi izigaba zokuqala ezinkulu zokuphila kwe-intrauterine? Ukususa ukubethela.

Sikhuluma ngombungu kusukela ekubukekeni kwengqamuzana lokuqala kulandela ukuhlangana phakathi kwe-spermatozoon ne-oocyte. Isigaba sombungu sibe sesihambisana nokukhula nokukhula komntwana ongakazalwa kusukela kulesi sigaba sokuqala kuze kube isonto lesi-8 lokukhulelwa (amasonto angu-10), okungukuthi izinsuku ezingu-56 emva kokuvundiswa.

Ichazwe kwezokwelapha ngezigaba ezingama-23 zeCarnegie, lesi sikhathi esibalulekile sempilo ye-intrauterine singahlukaniswa kalula sibe izigaba ezi-2 eziyinhloko:

• ukwakheka nokuhlukaniswa kwe-embryo kusukela ekukhuleni kuya evikini lesi-4 lokukhulelwa,
• uhlaka lwezitho ze-embryonic, kuze kube isonto lesi-8 lokukhulelwa.

Ngemva kokuvundiswa, i-embryogenesis iqala nge-zygote, ingqamuzana elilodwa elizalwa ngokuhlangana kwe-gamete yesilisa nesifazane futhi kakade liphethe ulwazi lofuzo lwengane ezayo. Emahoreni alandela ukwakheka kwayo, i-zygote iqala ukuhlukana, ngendlela ye-mitosis, ibe amangqamuzana amabili anobukhulu obulinganayo (ama-blastomeres), bese iba ngu-2, bese iba ngu-4 ngehora lama-8 ngemva kokuvundiswa, njll. -okuthiwa isigaba se ukuhlukaniswa.

Phakathi kwamahora angu-72 ngemva kokukhulelwa kanye nosuku lwesi-4 lokukhulelwa, umbungu uqala ukufuduka kwakhe kusukela eshubhu le-fallopian kuya esibelethweni ngenkathi ukuhlukana kwamaseli kuqhubeka. Ngemva kwalokho wakhiwe ngamangqamuzana angu-16, umbungu ufana nejikijolo, yingakho igama lawo i-morula. I-morula ibe isiguqukela ekubeni i-blastocyst, isigaba lapho amaseli ehlukanisa khona:

• i-peripheral cell layeri-trophoblast, isemsuka we-embryonic appendages okuzothi kamuva kube i-placenta,
• amaseli angu-3 noma ama-4 amaphakathi kakhulu (futhi amakhulu) e-blastocyst akha inqwaba yamaseli angaphakathi lapho umbungu uzovela khona: inkinobho ye-embryoblast noma ye-embryonic.

Phakathi kosuku lwesi-4 nolwesi-5 ngemva kokuhlangana, umbungu uqeda uhambo lwawo emgodini wesibeletho. Bese ilahlekelwa yimvilophi yayo yokuzivikela, i-zona pellucida. Futhi ebizwa ukuchanyuselwa, lesi sinyathelo esibalulekile senza kube lula ukunamathiselwa kwe-embryo emgqeni wesibeletho, futhi ekugcineni ezinsukwini ezingu-7 emva kokukhulelwa, ukufakwa.

Ngeviki lesibili nelesithathu lokukhulelwa (amaviki ama-4 nama-5), iqoqo lamaseli okwaze kwaba yileso sikhathi lakha i-embryo liyashintsha libe idiski le-embryonic elakhiwe izingqimba ezi-2 kanye nezi-3 (noma izingqimba zakudala). Bese sikhuluma isisu. Kulawa mashidi kuzophumela izicubu nezitho zengane engakazalwa futhi ikakhulukazi:

• i-ectoblast, ungqimba lwangaphandle, luzozalwa luyingxenye yesimiso sezinzwa, i-epidermis, ulwelwesi lwamafinyila noma amazinyo.
• kusuka ku-l'endoblaste, ungqimba lwangaphakathi, luzophumela ezithweni zesistimu yokugaya ukudla neyokuphefumula kanye nesibindi kanye namanyikwe ikakhulukazi.
• du i-mesoblast izovela ama-somite (emsuka wemisipha, imigqa, isikhumba noma uqwanga.), ama-gonads (amaseli ocansi esikhathi esizayo), izinso noma uhlelo lokujikeleza kwegazi.

I-embryogenesis idlula isigaba esisha esibalulekile phakathi nesonto le-4 lokukhulelwa (amaviki angu-6). Izendlalelo zakuqala zibe seziguqukela kusakhiwo esimise okwe-cylindrical C, ngaphansi komthelela wokugoqwa kwediski ye-embryonic. Lokhu ukunqunywa kwemingcele yombungu, into evumela ukuzungeza kwayo ngokuphathelene nama-appendages futhi ngaleyo ndlela ifanekisele i-anatomy yayo yesikhathi esizayo, yenzeka ngezigaba ezi-2:

• Lapho ugoba ohlangothini oluphambene, ikusasa lombungu, kulesi sigaba esichazwa ngokuthi i-dorsal protrusion, liyavela, umthamo we-amniotic cavity uyakhula, umbungu nama-appendages awo abuyele kuwo ngokwawo.
• Ngesikhathi se-longitudinal inflection, izifunda ze-cranial ne-caudal zombungu ziyahlangana

Njengoba ichazwe kahle, manje intanta emgodini we-amniotic, umbungu uyaqhubeka nokukhula:

kuvela amaqabunga ezitho ezingaphezulu, inhliziyo iqala ukushaya, ama-somite okuqala angama-4-12 abonakala ohlangothini lwawo lomgogodla.

Isigaba se-embryonic kanye ne-organogenesis

Kusukela ngenyanga yesibili yokukhulelwa, izitho zombungu zikhula ngesivinini esikhulu. Kuyinto organogenesis.

• Ngaphansi komphumela wokuthuthuka okusheshayo kwesimiso sezinzwa, isigxobo se-cephalic sombungu (ikhanda layo) siyakhula futhi siguquguquke. Ngaphakathi, ubuchopho bangaphambili (ubuchopho bangaphambili) buhlukana kabili phakathi nesonto lesi-5 lokukhulelwa. Esinye isenzakalo esiphawulekayo kulesi sigaba: uhlaka lwezitho zomzimba.
• Cishe ngesonto lesi-6, kusekuqaleni komsele wokuzwa wangaphandle ukuvela, njengama-vertebrae, okwamanje abekwe eduze komgogodla, kanye nemisipha yangemuva. Ezinye izici ze-embryo kulesi sigaba: isisu sayo sinomumo wawo wokugcina futhi amaseli ocansi akudala akhona.
• Emasontweni angama-7 ukhulelwe, izitho ziyaqhubeka zikhula futhi ama-inter-digital grooves avela ezandleni nasezinzwaneni kuyilapho imisipha yenhliziyo ihluka.

Ekupheleni kwesonto lesi-8, i-organogenesis cishe isiphelile. Izitho zihlukene futhi kuzodingeka "zikhule" kuphela phakathi nesigaba se-fetus. I-embryo yona ithatha isimo somuntu ngokwandayo: ikhanda layo liyasukuma, intamo yayo manje seyakhiwe njengobuso bayo futhi ikakhulukazi izindebe zayo, ikhala, amehlo nezindlebe.

Emavikini ayi-9 okukhulelwa (amasonto ayi-11), umbungu uba umbungu. Isikhathi se-fetus, esisukela enyangeni yesi-3 yokukhulelwa kuze kube yilapho umntwana ezalwa kubonakala ngaphezu kwakho konke ukukhula kwezicubu nezitho. Kungalesi sigaba futhi lapho umbungu ethola khona ukwanda okukhulu kobukhulu nesisindo. Isibonelo esitshela ngokukhethekile: kusukela ku-3 cm no-11 g ekupheleni kwesikhathi se-embryonic, ingane ezayo idlula ku-12 cm no-65 g ekupheleni kwenyanga yesi-3 yokukhulelwa!