Blastula az miqdori ziyodi blastameraho iborat buda (ma- salan, dar neshtarshaklho az 3000 hujayra), dar rafti inkishof ba davrai nav meguzarad, ki gastrula (az kalimai yunoni daz1go – meda) nom dorad. Dar in davra janin az qabathoi judoshudai hujayragi – bargchahoi janin iborat ast. Qabati beruniro ekto- derma (az kalimai yunonii es1o – berun) va daruniro entoderma (az kalimai yunonii ep1o – darun) menomand. Majmui ravandhoe, ki ba paydoishi gastrula musoidat mekunand, gastrulyatsiya nomi- da meshavad.
Dar neshtarshaklho gastrulyatsiya dar natijai furu raftani yak tarafi devorai blastula, ki dar natija javfi avvali jism paydo meshavad, ba vujud meoyad.
Baroi isboti in guftaho tubi surokhshudai kudakonro misol meorem. Tubi rangini reziny az mobayn bo khat judo shudaast. Agar tubro tarze guzorem, ki shakli kosa paydo shavad, devorai on az du qabat iborat buda, ba shakli gastrulai neshtarshaklho monand meshavad. Dar in holat vazifai ektodermaro qabati bo- loy va vazifai entodermaro qabati daruny (fururafta) ijro me- kunad. Dar hayvonoti serhujayra, gayr az rudakovokho, barobari gastrulyatsiya qabati seyumy yo bargaki janin mezoderma (az kalimai yunonii te8O8 – dar mobayn joy giriftan) niz paydo meshavad.
Mezoderma az majmui unsurhoi hujayragy, ki dar bayni ekto va entodermai javfi avvalini jism joy dorand, iborat ast. Bo paydo shudani mezoderma janin seqabata meshava.
Hamin tavr, mohiyati ravandi gastrulyatsiya dar on ast, ki massai hujayraho bo ham omezish meyoband, vale hujayrahoi ja- niny taqsim nameshavand va namesabzand. Dar hamin davra isti- fodai akhbori genetikii hujayrahoi janin sar shuda, alomathoi nakhustini tafriqashavy ba nazar merasand.
Tafriqashavi ravandi paydoishi tafovut va ziyod shudani sokh- tor va vazifa dar bayni hujayrahoi alohida va qismhoi janin meboshad. Az nuqtai nazari morfologi tafriqa shudan ba vujud omadani sadho nav hujayraho, ki sokhtorashon makhsus va az ham- digar farqkunanda meboshand.
Az nigohi biokhimiyavi boshad, tafriqashavi makhsus gardida- ni hujayraho bahri sintezi safedahoi muayyan meboshad, ki bo ha- mon navi hujayraho khossand. Masalan, dar pust, dar hujayrahoi epiteliya keratin sintez meshavad. Dar eritrositho gemoglobin, dar hujayrahoi boftai gadudi zeri meda insulin va gayra sin- tez meshavad.
Makhsusgardii biokhimiyavii hujayra faoliyati farqkunii genhoro tamin namuda, dar hujayrai bargakhoi janini, ki ba uzvho va sistemahoi muayyan ibtido meguzorand ba tafovut hosil kardani genho musoidat menamoyand.
Dar natijai tafriqai hujayrai bargakhoi janin az hisobi ektoderma silsilai asab, uzvhoi his, pust, siri dandon ba vujud meoyad. Az entoderma boshad, rudai mobayni, gadudhoi hazmi khurok, jigar va gadudi zeri meda, galsama va shush, az mezoderma boftai mushaki, boftai payvandi, sistemai gardishi khun, gur- daho, gadudhoi jinsi va gayra tashakkul meyoband. Dar jonvaro- ni gunogun az bargakhoi yakkhelai janin uzvu boftahoi yakkhela ba vujud meoyand. In daleli monandii onhost.
Monandii bargakhoi janini aksari hayvonot isboti yagona- gii olami hayvonot meboshad.
Organogenez
Badi ba okhir rasidani gastrulyatsiya dar janin uzvhoi mar- kazi, ba monandi naychai asab, khorda, naycharuda paydo meshavand. Dar neshtarshaklho uzvhoi markazi ba chunin roh tashakkul meyo- band (rasmi 7.4).
Rasmi 7.4. Umumiyati khathoi uzvho dar neshtarshaklon:
A – gastrula, B, V – tashakkuli naychai asab, G – tashakkuli khorda, naychai ruda va mezoderma, 1 – ektoderma, 2 – entoderma, 3 – mezo- dermai ibtidoi, 4 – javfi ruda, 5 – qabati asab, 6 – naychai asab, 7 – khorda, 8 – javfi duyumini badan.
Ektodermai tarafi takhtapusht kham gashta, ba novacha tabdil meyobad. Ektodermai jonibhoi chap va rost boshad, meafzoyad va bo- loi novacharo mepushonad. Novacha ibtidoi silsilai asab buda, ba ektoderma furu meravad va pahluhoi on bo ham payvast meshavand.
Hamin tavr, naychai asab ba vujud meoyad. Az qismi digari boqimondai ektodermai ibtidoi pustparda paydo meshavad. Dar in zina janinro neyrula menomand. Qismi takhtapushtii ento- derma, ki dar zeri asab joygir ast, az digar qismho judo shuda, pechutob mekhurad va tasmaero ba vujud meorad, ki onro khorda me- nomand. Az qismi boqimondai entoderma, mezoderma va epitelyai ruda inkishof meyobad. Tafriqashavii minbadai hujayrahoi ja- nin ba paydo shudani bargakhoi bisyori ozod, yane uzvu boftaho ovarda merasonad.
Induksiyai janin
Mushohidahoi hujayratukhmi bordori qurboqqa imkon do- dand, ki tarzi inkishofi hujayrahoi in yo on qismi janin omukhta shavand. Malum gardid, az hujayrahoe, ki dar blastula joyhoi munosib dorand, uzvhoi avvalin ba vujud meoyand. Hamchunin, muqarrar shud, ki az kadom guruhi hujayraho naychahoi asab, khor- da, mezoderma, epetiliyai pust paydo meshavand. Dar haqiqat, dar organizmhoi qobili inkishof (ugto) az hujayrahoi muayyani ib- tidoi uzvu boftahoi muayyan ba vujud meoyand, vale dar mavridi berun az organizm parvarish kardani hujayrahoi janin (dar pro- birka ^ygo) onho in qobiliyatro gum mekunand.
CHaro hujayrai janin ba bofta yo uzvi mushakhkhas tabdil meyobad?
Ba in savol bori nakhust olimi barjastai olmoni, asosguzori embriologiyai tajribavi G.SHpeman maroq zohir namudaast.
Solhoi 20-30-yumi asri HH SHpeman chunin tajriba guzaro- nid. Az janini qurboqqa dar davrai avvali gastruli manshai khorda va hamrohi on manshai mezodermaro burida, ba zeri ekto- dermai janini digar, ki az vay boyad pust paydo meshud, joygir kard (rasmi 7.5).
Rasmi 7.5. Naqshai kuchonidai qismi janin dar davrai avvali gastrula:
- – khordomezodermai ibtidoi,
- – javfi blastula.
Dar joyi chaspishi qismi kuchonida bo ektoderma az hisobi hujayrahoi ibtidoy pustparda dar janini naychai duyumi ilova- gii asab paydo shud, vale az hujayrahoi begona boshand, khorda va mezoderma ba vujud omadand. Dar tajribahoi digar dar joyi ku- chonidashuda yak sistemai tomi uzvhoi markazy, ba monandi asab, khorda, mezoderma (rasmi 7.6) tashakkul yoftand. Hamai in digar- guniho dar barobari inkishofi mutadili qismhoi digari ja- nin ba amal meoyand. Holatero, ki yak guruhi hujayrahoi ibtidoy ba qismi digari janin tasir merasonand, induksiyai janini me- nomand. Induksiyai janini dar inkishofi janin ahamiyati kalon dorad. Agar dar zinai avvali gastrula hujayrahoi ibtidoii khor- daro purra girifta partoem, on goh naychai asab tamoman inki- shof nameyobad. Dar surati ba joyi ekdodermai takhtapushti janin (az vay naychai asab paydo meshavad) ba vujud omadani pustparda,
janin mahv megardad.
Rasmi 7.6. Janini avval
(az bolo) va duchori induksiya shudani samandar (az poyon):
- – naychai yakumini asab,
- – khorda,
- – naychai asabi induksiyashuda;
- – khordae, ki az janini kuchonida inkishof meyobad.
Dar natijai omuzishi inkishofi janin malum gardid, ki ogozi tashakkuli khorda na faqat bo induktori naychai asab, bal- ki ba induksiyai hujayrahoi ibtidoii silsilai asab niz muhtoj ast.
Dar davrai inkishofi janin induksiya yaktarafa nabuda, bal- ki tasiri mutaqobilai qismhoi janin ba vujud meoyad. Hamin tavr, metavon ba chunin khulosa omad: holate, ki dar jarayoni em- briogenez qismi avvali janin ba qismi digari on tasir rason- da, rohi inkishofi onro muayyan mekunad, induksiyai janini no- mida meshavad.
Savolho baroi sanjish:
- Inkishofi janini hayvonot chi guna ast?
- Davrahoi inkishofi janini hayvonoti serhujayraro nombar kuned.
- Davrahoi porashaviro sharh dihed.
- Farqi porashavi az taqsimshavii mitozii hujayrahoi hayvon dar chist?
- Janini duqabata chi guna paydo meshavad?
- Dar rafti inkishofi janin kadom bargakho paydo meshavand?
Istilohot:
- Davrai janini – davrai inkishofi organizm az vaqti ba vuchud omadani zigota to tavallud shudan yo az pardai tukhm berun baromadan.
- Induksiya – tasiri yak bofta (chanin) ba qismhoi digari chanin dar rafti embriogenez rafti inkishofi onro dar oyanda muayyan mekunad.
- Porashavi (taqsimshavi) – ravandi paydo shudani chanini yakqabat, yane blastula.
- Gastrulyatsiya – ravandi paydo shudani chanini duqabata, yane gastrula.
- Bargakhoi chanin – qabathoi alohidai huchayraho, ki dar chanin choyi muayyanro doshta, uzvu bofthoi mushakhkhasro paydo mekunand.
- Organogenez – paydoish, tashakkul va tafriqshavii uzvho dar in- kishofi chanini.
- Ontogenez – machmui hodisahoe, ki dar organizm az vaqti paydo shudani zigota to favti onro dar bar megirad.
Testho
- Blastula az chand blastomeraho iborat ast?
a) dahiho; b) sadiho; v) hazorho.
- Gastrula az chi paydo meshavad?
a) blastomeraho; b) blastula; v) bargchahoi chanin.
- Janin az chand qabat iborat ast?
a) du; b) se; v) chor.
- Gastrula az kadom zabon girifta shudaast?
a) anglisi; b) lotini; v) yunoni.
- Dar kadom davr tafriqashavii alomatho ogoz meshavad?
a) blastulaho; b) gastrulaho; v) blastomerho.
- Tafriqashavi chist?
a) makhsusgardonidani huchayra va bofta baroi vazifai muayyan;
b) farqi sokhtori huchayra; v) inkishofi blastomera.
- Az ektoderma chi paydo meshavad?
a) uzvhoi his; b) galsama va shush; v) gurdaho.
- Organogenez chist?
a) paydoishi uzvho va tafriqashavii onho; b) bohamtasirii uzvho;
v) farqi uzvho.
- Asosguzori induksiyai chanin ki bud?
a) G.SHpeman; b) F.Myuller; v) I.Mechnikov.
- Induksiyai janin chi mano dorad?
a) mudome, ki yak guruhi hujayrahoi ibtidoi ba qismi janini digar tasir merasonand.
b) bohamvobastagii hujayraho; v) bohamvobastagii boftaho.