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-umi asri HH SHpeman chunin tajriba guzaronid. Az janini qurboqqa dar davrai avvali gastruli manshai khorda va hamrohi on manshai mezodermaro burida ba zeri ektodermai janini digar, ki az vay boyad pust paydo meshud, joygir kard (rasmi 7.5).

Dar joi chaspishi qismi kuchonida bo ektoderma az hisobi hujayrahoi ibtidoi pustparda dar janini naychai duyumi ilovagii asab paydo shud. Vale az hujayrahoi begona boshand, khorda va mezoderma ba vujud omadand. Dar tajribahoi digar dar joi kuchonidashuda yak sistemai tomi uzvhoi markazi, ba monandi asab, khorda, mezoderma (rasmi 7.6) tashakkul yoftand. Hamai in dagarguniho dar barobari inkishofi mutadili qismhoi digari janin ba amal meoyand.

Holatero, ki yak guruhi hujayrahoi ibtidoi ba qismi digari janin tasir merasonand, induksiyai janini menomand. Induksiyai janini dar inkishofi janin ahamiyati kalon dorad. Agar dar zinai avvali gastrula hujayrahoi ibtidoii khordaro purra girifta partoem, on goh naychai asab tamoman inkishof nameyobad. Dar surati ba joi ekdodermai takhtapushti janin (az vay naychai asab paydo meshavad) ba vujud omadani pustparda, janin mahv megardad.

Dar natijai omuzishi inkishofi janin malum gardid, ki ogozi tashakkuli khorda nafaqat bo induktori naychai  asab, balki ba induksiyai hujayrahoi ibtidoii silsilai asab niz muhtoj ast. Dar davrai inkishofi janin induksiya yaktarafa nabuda, balki tasiri mutaqobilai qismhoi janin ba vujud meoyad. Hamin tavr, metavon ba chunin khulosa omad: holate, ki dar jarayoni embriogenez qismi avali janin ba qismi digari on tasir rasonda, rohi inkishofi onro muayyan mekunad, induksiyai janini nomida meshavad.

Savolho baroi sanjish:

1. Inkishofi janini hayvonot chi guna ast?
2. Davrahoi inkishofi janini hayvonoti serhujayraro nom- bar kuned.
3. Davrahoi bulakshaviro sharh dihed.
4. Farqiyati bulakshavi az taqsimshavii mitozii hujayrahoi hayvon dar chist?
5. Janini duqabata chi guna paydo meshavad?
6. Dar rafti inkishofi janin kadom bargakho paydo meshavand?

Istilohot:

1. Davrai janini – davrai inkishofi organizm az vaqti ba vujud omadani zigota to tavallud shudan yo az pardai tukhm berun baromadan.
2. Induksiya – tasiri yak bofta (janin) ba qismhoi digari janin dar rafti embriogenez rafti inkishofi onro dar oyanda muayyan mekunad.
3. Porashavi (taqsimshavi) – ravandi paydo shudani janini yakqabat, yane blastula.
4. Gastrulyatsiya – ravandi paydo shudani janini duqabata, yane gastrula.
5. Bargakhoi janin – qabathoi alohidai hujayraho, ki dar janin joi muayyanro doshta, uzvu bofthoi mushakhkhasro paydo mekunand.
6. Organogenez – paydoish, tashakkul va tafriqshavii uzvho dar inkishofi janini.
7. Ontogenez – majmui hodisahoe, ki dar organizm az vaqti paydo shudani zigota to favti onro dar bar megirad.