Neurula - ib theem ntawm txoj kev loj hlob embryo

Ib tug ntawm lub sij hawm ntawm tus neeg txoj kev loj hlob ntawm tus kab mob no - ontogenesis yog embryogenesis. Nws muaj xws li lub sij hawm los ntawm thaum pib ntawm lub tsim ntawm lub zygote ua ntej yug tus me nyuam kab mob thiab muaj ob peb successively dua theem. Ib tug ntawm lawv yog neurula. Qhov no yog cov theem ntawm kev loj hlob ntawm vertebrates, uas ua rau yus mus rau tsim ntawm lub embryo, muaj peb kab khaubncaws sab nraud povtseg, raws li zoo raws li lub neural raj. Tsis tas li ntawd, rau ob peb lub lis piam nyob rau hauv lub embryo yog tsim ntawm lub ntsiab yam ntxwv ntsiab ntawm tag nrho cov central thiab peripheral lub paj hlwb. Nyob rau hauv no tsab xov xwm peb xav txog cov yam ntxwv ntawm ob qho tib si rau cov theem thiab cov physiological dab noj qhov chaw nyob rau hauv nws.

Cov qib embryonic txoj kev loj hlob

Tag nrho thiab niaj hnub crushing zygote placental tsiaj, uas muaj xws li cov neeg, nws leads mus rau ib tug qauv zoo li ib tug txiv hmab txiv ntoo mulberry los yog txiv pos. Nws yog hu ua ib tug morula. Ces nws hlwb teem nyob rau hauv ib tug txheej, thiab tsim nyob rau blastula. Qhov no hollow hnab, cov phab ntsa uas raug tsim blastomeres-hlwb. Tom ntej no, ib tug txheej txheem ntawm invagination, uas ua rau cov tsos ntawm ib tug muab ob npaug rau txheej ntawm lub embryo. Qhov no yog cov theem gastrula. Nws muaj ectoderm thiab endoderm, thiab muaj ib tug thawj qhov ncauj, hu ua di ncauj ntawm lub blastopore. Tom qab ntawm cov npoo yog raug kaw, thiab cov me nyuam hauv plab muaj hauv daim ntawv ntawm ib tug muab ob npaug rau txheej ntawm lub hnab. Tom ntej teeb meem nyob rau hauv lub embryo qauv hais txog mus rau lub tsos ntawm lwm, lub thib peb, lub germinal txheej - mesoderm dag ntawm lub ecto- thiab endoderm. Nws kawm ntawv nyob rau tib neeg embryogenesis nws muaj nws tus kheej specifics. Peb yuav kawm txog nws nyob rau hauv kom meej.

tsim ntawm mesenchyme

Tib neeg embryo nyob rau hauv nws cov kab noj hniav ntaub ntawv cais sab dab - somites los yog hnab ris. Lawv muab tau los ntawm cov txheej thaum ub plab phab ntsa. Los ntawm cov kev tsim mesoderm thiab somites nws ua hauj lwm pab raws li ib lub teeb liab mus rau lub sab saum toj organogenesis. Tsim ib tug system cov tseem ceeb tshaj plaws lug: notochord, hnyuv thiab neural raj. Lawv hu ua axial kabmob. Kab ntawm complicating nws cov qauv, tsim ib lub tshiab rau theem - neurula. Nws yuav siv sij hawm qhov chaw nyob rau 3 - 4 lub lis piam uas cev xeeb tub. Lub mechanism ntawm tsim ntawm hais tias siab dua embryo theem sib tham ntxiv.

Raws li cov embryo tshwm neural raj

Cov txheej daim ntawv germinal - ectoderm, nyob rau hauv nraub qaum ntawm fetus yuav ntau tuab thiab tuab, thiab yog hloov dua siab tshiab rau hauv lub neural phaj. Nws sawv raug tsa sawv rov, txoj kev ua ob chais. Nruab nrab ntawm lawv muaj ib tug los ntawm channel, tom qab transforming mus rau cov kab noj hniav ntawm lub paj hlwb thiab tus txha caj qaum sau nrog cawv. Neural phaj kaw cov npoo, thawj nyob rau hauv lub tsev me nyuam cheeb tsam ntawm lub embryo, lub embryo thiab ces rov qab nrog lub cev axis. Xaus nrog lub kaw ntawm lub neural phaj nyob rau hauv lub cranial ib feem nyob qhov twg lub tsim lub hlwb hlwv - pib ntawm lub paj hlwb. Los ntawm 4 lub lis piam uas cev xeeb tub, cov neural raj yog kiag li segregated los ntawm cov ectoderm. Vim hais tias neural raj tsim paj hlwb thiab trophic cov ntaub so ntswg - tshwm sim neurula thiab neuroglia. Qhov no yog cov theem ntawm embryonic txoj kev loj hlob, uas muaj peb kab khaubncaws sab nraud povtseg thiab neural raj. Yuav ua li cas yuav los ntawm nws tsim tib neeg lub paj hlwb?

Lub luag hauj lwm ntawm neural Crest tsim nyob rau hauv lub paj hlwb

Tam sim ntawd tom qab lub koom chais thiab cov tsos ntawm cov neural raj nyob rau hauv lub central feem thiab cutaneous ectoderm cais ib pab pawg neeg ntawm lub hlwb. Nws yog nyob raws lub axis ntawm lub embryo lub cev nruab nrab ntawm cov txheej txheej thiab lub embryonic neural raj no yog hu ua cov neural Crest. Nws cellular ntsiab muaj ib tug tshwj xeeb feature. Qhov no yog - lub peev xwm los tsiv mus nyob rau ntau qhov chaw ntawm tus tib neeg embryo. Piv txwv li, ib co ntawm cov embryo hlwb tsiv mus ntxaum mus rau hauv lub cev thiab daim ntawv neurocytes thiab neuroglia ganglia ntawm sympathetic thiab parasympathetic cov pawg ntawm cov peripheral ib feem ntawm lub paj hlwb. Lwm yam hlwb nyob twj ywm nyob rau hauv lub neural Crest, chiv txoj kev ua ib ganglion phiaj, uas yog ces hloov mus rau hauv ntshav 31 officers ntawm hlwb txha nqaj qab haus huv. Nyob rau hauv tus txheej txheem no neurulation tsis xaus thiab muaj ib tug ntxiv kev txhim kho ntawm lub qhov chaw ntawm lub hauv paus thiab peripheral lub paj hlwb.

Cov ua complexity ntawm cov qauv ntawm cov embryo nyob rau theem neurula

Migrating neural Crest hlwb, xws li los ntawm intermediate feem tom ntej no mus rau lub sacral qaum khej ntawm 27 - 28 somites, muaj lub peev xwm yuav qha, uas yog yeej tseem zoo tib yam polustvolovym hlwb ntawm hlwb pob txha. Pib los ntawm lub tom ntej no feem ntawm lub diencephalon mus rau lub sacral card embryo ntawm 27 - 28 somite officers, tus tsim ntawm mature neurocytes thiab glial hlwb ntawm lub cranial qab haus huv thiab ganglia ntawm lub hnov thiab vestibular apparatus. Rau ntawm no theem ntawm embryonic txoj kev loj hlob nyob rau hauv ntau ntawm 1 mus rau 7 somite derivatives Crest pib lub tsim ntawm autonomic ganglia innervating lub plawv, lub ntsws, cov hnyuv thiab kabmob ntawm lub embryo plab mog. Ua kom tiav cov maturation ntawm poob siab system yog txog li 40 lub lis piam uas cev xeeb tub.

Yog vim li cas rau lub tsiv teb tsaws ntawm neural Crest hlwb

Raws li cov saum toj no tham txog dab ntawm poob siab system, ib tug tej yam ntuj tso lo lus nug tshwm sim: yuav ua li cas ua koj piav yog vim li cas rau mus rau neural Crest hlwb tshaj ntev ncua kev nyob rau hauv lub cev ntawm lub fetus? Niaj hnub nimno embryology piav rau lawv raws li nram qab no. Firstly, neurula - ib theem ntawm embryogenesis uas neural Crest hlwb tsis tau lawv lub peev xwm los ua raws li, piv txwv li kev sib txuas lus nrog txhua lwm yam ... Qhov thib ob yog vim li cas cov lus dag nyob rau hauv lub tshuaj nyob tus yeees ntawm cov extracellular matrix ntawm lub embryo. Nws yog tsim los ntawm cov hyaluronic acid thiab proteins: collagen, laminin, fibronectin muaj tropism rau neural Crest hlwb.

Lawv kev sib raug nrog tus extracellular matrix thiab tsiv teb tsaws tshwm sim vim taw molecules - integrins, raws li zoo raws li lub nyob rau hauv lub somites neurula tshwj xeeb glycoproteins: tenascin thiab T-cadherin. Tag nrho cov no kom txoj kev loj hlob ntawm lub ntsiab qhov chaw ntawm poob siab system ntawm lub embryo.