I-Neurula yisiteji sokuthuthukiswa kombungu

Enye yezikhathi zokuthuthukiswa komuntu ngamunye - i-ontogenesis, i-embryogenesis. Kuhlanganisa isikhathi kusukela ekuqaleni kokubunjwa kwe-zygote kuze kube nokuzalwa komzimba futhi kuqukethe izigaba eziningana ezilandelanayo. Omunye wabo yi-neurula. Lesi yisiteji sokuthuthukiswa kwezilwane ze-vertebrate, okuholela ekwakhiweni kombungu onamagciwane amathathu, kanye ne-tube ye-neural. Ngaphezu kwalokho, kungakapheli amasonto ambalwa i-embryo yenza ukwakheka kwezakhi eziyisisekelo zomzimba kuzo zonke izingxenye zesistimu yezinzwa eziphakathi nendawo. Kulesi sihloko, sizocubungula izici zombili esiteji ngokwawo kanye nezinqubo zokuphila ezenzeka kuyo.

Izigaba zokuthuthukiswa kwamabriyoni

Ukuchotshozwa okugcwele nokufanako kwe-zygote yezilwane ezincelisayo, okuhlanganisa umuntu, kuholela ekubukeni kwesakhiwo esibonakala njengomuthi wamabhilikhi noma okusajingijolo. Ibizwa ngokuthi i-morula. Khona-ke amangqamuzana ayo aphakama emgqeni owodwa, kanye namafomu e-blastula. Liyisaka elingenalutho, izindonga zalo ezakhiwa ngamaseli e-blastomere. Khona-ke kunenqubo yokungena ngemvume, okuholela ekubukeni kombungu onomabili. Lesi yisiteji se-gastrula. Iqukethe i-ectoderm ne-endoderm futhi inomlomo oyinhloko, obizwa nge-lip blastopore. Kamuva, emaphethelweni ayo avaliwe, futhi umbungu unokubonakala kwesikhwama esinezinhla ezimbili. Izinkinga eziqhubekayo esakhiweni se-embryo ziphathelene nokubukeka kwesinye esinye, sesithathu, se-embryonic layer - i-mesoderm, elele phakathi kwe-ecto- ne-endoderm. Imfundo yakhe embryogenesis yomuntu inemininingwane yayo. Masifunde ngokuningiliziwe.

Ukubunjwa kwe-mesenchyme

Umbungu womuntu emgodleni wayo udala iminyango engezansi - okuyi-somites noma amapokhethi. Zitholakala edongeni lomathumbu oyinhloko. Kulezi zinhlobo, i-mesoderm iqala futhi lokhu kuyisibonakaliso sokuqala kwe-organogenesis. Isakhiwo sezakhiwo ezibalulekile sakhiwa: i-chord, intumbo, kanye ne-neural tube. Bathola igama lamalungu axial. I-embryo iyancipha isakhiwo sayo, yakha isiteji esisha - neurula. Lokhu kwenzeka emavikini amathathu kuya ku-4 okukhulelwa. Indlela yokwakha ngaphezulu kwalesi sigaba sombungu izocatshangelwa ngezansi.

I-embryo ihlakulela kanjani i-neural tube

Iqabunga elingaphandle le-embryonic liyi-ectoderm, ohlangothini lwe-dorsal lwe-fetus luba denser futhi lukhulu kakhulu, futhi luba yi-plate yezinzwa. Amaphethelo alo aphakama phezulu, enza ama-plates amabili. Phakathi kwabo kubonakala umzila ohamba phambili, ozoguqula kamuva ube yingxenye yobuchopho nomgogodla, ogcwele utshwala. I-plate nerve ivala imiphetho yayo kuqala esifundeni somlomo wesibeletho, bese ubuyela emuva emzimbeni womzimba we-embryo. Ukuvala i-plateau ye-neural iphetha engxenyeni ye-craneal, lapho ukuqhuma kobuchopho kukhula khona-izizinda zezindawo zobuchopho. Ngeviki le-4 lokukhulelwa, i-neural tube itholakala ngokuphelele ectoderm. Kusukela ku-tube ye-neural kwakhiwa amaseli we-nerve, kanye nezicubu ze-trophic - neuroglia ne-neurula. Lesi yisiteji sokuthuthukiswa kombungu, okuqukethe amaqabunga ama-embrionic amathathu kanye ne-neural tube. Isimiso sezinzwa zesintu senza kanjani kuso?

Indima ye-neural crest ekubunjweni kwesimiso sezinzwa

Ngokushesha ngemva kokuvalwa kwama-rollers kanye nokubonakala kwe-tube ye-neural ezindaweni ezingaphakathi ne-dermal ectoderm, iqembu lamaseli libuyiselwa. Itholakala eduze kwe-axis yomzimba wombungu phakathi kwezingqimba zangaphandle ze-embryonic kanye ne-neural tube futhi kuthiwa yi-neural crest. Izakhi zalo zamaselula zinezinto eziyingqayizivele. Lona ikhono lokuthuthela ezingxenyeni ezihlukene zombungu womuntu. Isibonelo, amanye amangqamuzana ahambela emzimbeni wombungu bese enza ama-neurocytes kanye neuroglia ye-ganglia yezingxenye ezizwelana nozwela zengxenye yesistimu yezinzwa. Amanye amangqamuzana ahlala esiqhingini esinamahloni kakhulu, ekuqaleni adala amapulangwe angama-ganglionic, aphinde aguqulwe abe yiziqephu ezingu-31 zombili wezinzwa zomgogodla. Izinqubo ze-neurulation azipheli lapho, futhi ukuthuthukiswa okuqhubekayo kwenziwa kwezinye izingxenye zesistimu yezinzwa eziphakathi nendawo.

Ukuphikisana kwesakhiwo se-embryo esigabeni se-neurula

Ukufuduka kwamangqamuzana e-neural crest, okuqala kusukela esifundeni sesikhathi esizayo ebuchosheni obuphakathi phakathi kwe-sacral ezingeni lama-27 kuya ku-28 somites, unamandla okuhlukanisa, okungukuthi, okufana ncamashi namaseli aphikisiwe amaminithi omnkantsha obomvu. Kusukela esifundeni sengqondo esizayo esiyingqungquthela engxenyeni yama-sacral embryo ezingeni lama-27 kuya kwangu-28 ngamabili, ama-neurocyte avuthiwe nama-glial cell of the craneal neerves, kanye nama-node nerve of the instrumentory and vestibular devices. Kulesi sigaba sokuthuthukiswa kwamabryonic esifundeni kusuka ku-1 ukuya ku-7 somite, iziqephu ze-neural crest ziqala ukwakhiwa kwe-ganglia yesimiso sezinzwa ezizimele, esilungisa inhliziyo, amaphaphu, amathumbu kanye nezitho zomzimba. Ukuqeda ukuvuthwa kwesimiso sakhe sezinzwa kwenzeka emavikini angama-40 okukhulelwa.

Izimbangela zokufuduka kwamaseli we-neural crest

Ukuqhubeka kusukela kwezinqubo ezingenhla zokwakhiwa kwesimiso sezinzwa, kuphakama umbuzo wemvelo: kanjani ukuchaza isizathu sokuhamba kwamaseli we-neural crest emabangeni amade emzimbeni we-embryo? I-embryology yanamuhla iyichaza kanje. Okokuqala, i-neurula yisiteji se-embryogenesis, lapho amangqamuzana e-neural crest alahlekelwa amandla okunamathela, okungukuthi, izibopho komunye nomunye. Isizathu sesibili sisekwakhiweni kwamakhemikhali we-intercellular matrix embryo. Iqukethe i-hyaluronic acid namaprotheni: i-collagen, i-laminin, i-fibronectin, ene-tropism emaqenjini e-neural crest.

Ukuxhumeka kwabo ne-matrix extracellular nokufuduka kwenzeka ngenxa yokusayina ama-molecule - okuhlanganiswa, kanye nokuba khona kwama-glycoprotein akhethekile ezindaweni ezithile ze-neurula: i-tenascin ne-T-cadherin. Konke lokhu kuqinisekisa ukuthuthukiswa kwezinxenye eziyisisekelo zesimiso sezinzwa ze-embryo.