Phuhliso osandul

ixesha osandul, obizwa ngokuba embryogenesis, esuka ambaxa eziba gametes ababhinqileyo kunye abangamadoda kwaye imele inkqubo sisetyenzisiwe. Ngoko ke, abo eziphilayo badla pre-natal uphuhliso, embryogenesis iphela ngokuzalwa, xa eziphilayo nohlobo lophuhliso mibungu - beshiya inwebu osandul.

phuhliso osandul has izigaba ezininzi:

1.Zigota. Ekukhulelweni oyindoda iseli ngesondo, lwathi iqanda, Nokumphikisa lwalo lokukhawulelana nophuhliso. Baqale kwenzeka inkqubo yemichiza emzimbeni ukuba igalelo ekwakhiweni yolingano beqanda, eziba nokuphelisa inwebu, kubangele ezimbini fuse yeseli nuclei, kwaye ukusekwa DNA.

2. lokutyunyuzwa (kwinqanaba lokuqala yophuhliso elilodwa) - iCandelo elilodwa. Xa iqanda, nto leyo ihamba phantsi ityhubhu Imibhobho, vee kwakheka, apho kukho division cell. Senziwe ngale kwiiseli ndlela kuthiwa morula. Eli nyathelo wavavanywa zonke izinto multicellular ukuba zizala ezahlukeneyo kuphela inkqubo kwisahlulo iseli (iphiramidi ebonisa unxibelelwano, zangababini, spiral).

A feature of division iseli kukuba akukho kukhula. Le nkqubo ibandakanya ukuyilwa iiseli enye enkulu (iqanda) inani elikhulu iiseli ezincinci kukho icytoplasm ezimbalwa kufuphi eziba.

ixesha osandul ayipheli apha, cinga uphuhliso ilandelayo umbungu yeqonga.

3. Le blastula (ukuyilwa kwezakhiwo multicellular ngohlobo kwiqamza) - iquka umaleko iiseli ukuba zibizwa ngokuba osandul '. ubukhulu blastula siwungena ubungakanani iqanda, ngoko ngexesha kwisahlulo iseli, inani eziba kunye nokunyuka DNA.

4. Gastrulation - step intshukumo kweeseli osandul, nto uluhlu lwe maleko ezintathu iphepha osandul. Eli nqanaba libizwa ebalasele ukwanda Yindibanisela iiprothini kunye ribosomes, kweli xesha kukho Buze kwisibonda (kwezityalo) blastula ngaphakathi, nezibonda esahlukileyo uxhulumanisa, kwaye umngxuma iyapheliswa blastula. Oku kwenza umngxuma entsha, ebizwa blastopore okanye umlomo ephambili.

Ngoko ke, uphuhliso bungu torque gastrulation kuyimfuneko, ekubeni ixesha osandul kwesi sigaba yenza ukuyilwa amalungu ayo kunye namalaphu kunye neenkqubo omzimba.

Kufuneka kuqatshelwe, ukuyilwa ancedisana amalungu umbungu ngamaxesha ahlukeneyo abe uvakalelo ezahlukeneyo kwiimpembelelo eyonakalisayo kokusingqongileyo, ezifana izifo, imitha okanye arhente imichiza. La maxesha ubukhali ukwanda kuthiwa kakhulu, kukho ukwanda okuba ukungaqheleki asakhasayo.

Umzekelo, ixesha osandul yi ezimbalwa iingongoma ezibalulekileyo. Makhe sihlolisise ngokweenkcukacha ngaphezulu:

1. ixesha blastula (kwiiveki zokuqala ezimbini emva kokukhulelwa) - umbungu mhlawumbi yafa, okanye iyaqhubeka ukuba nokuguquguquka ngaphandle ezinxaxhileyo. Ngeli xesha inani elikhulu iyafa iimbumba (40%), eyaqala uphuhliso lwabo zeeseli lwegciwane mutated.

2. Ngomhla wamashumi amabini ngosuku seventieth emva kokukhulelwa - ixesha semngciphekweni omkhulu ndiseyimbumba njengoko uqale mawubekwe ukwenza onke amalungu abalulekileyo.

3. Ithuba ezingekazalwa luphawulwa ukukhula ngokukhawuleza olungekazalwa. apho Apha kaninzi inokuba kophulwa yophuhliso yayo kuphela kwezo amalungu, abo azigqitywanga nokudaleka.

Ngoko ke, ixesha osandul ontogenesis luphawulwa nokusekwa kunye nophuhliso umbungu kwiyantlukawano iseli, ukubunjwa waba tissue, amalungu kunye neenkqubo. eziphilayo ezahlukeneyo ziyahluka kwesi sihlandlo sexesha, kodwa kunjalo, iqala kwi akhulelwe iphela kunye nokuzalwa ubomi obutsha.