Embryonic period ukuthuthukiswa

embryonic period, ukubizwa ngokuthi embryogenesis, evela ekhuthaza we nuclei of gametes kwabesifazane nabesilisa futhi imele inqubo kokukhulelwa. Ngakho, labo eziphilayo bathambekele pre-natal ukuthuthukiswa, embryogenesis iphela ukuzalwa, e eziphilayo nohlobo ukuthuthukiswa elalikudle lapho liseyisibungu - kokushiya ulwelwesi sombungu.

Embryonic period ukuthuthukiswa has izigaba eziningana:

1.Zigota. Ngesikhathi sokukhulelwa wesilisa ocansini cell, ekufinyeleleni iqanda, ingqondo ukuthuthukiswa yayo. It kuqale nokuqala ukwenzeka yezinqubo zamakhemikhali ngokomzimba anomthelela kumiswa wesimethri neqanda, nokuqedwa ulwelwesi nuclei, okuholela ezimbili cell nuclei fuse, futhi kwakhiwa DNA.

2. kwasani (esigabeni sokuqala yentuthuko zygote) - a division of the zygote. Ngo iqanda, okuyinto ihamba phansi tube fallopian, anemifantu akhiwa, lapho kukhona cell division. Obakheka ngale ndlela abizwa ngokuthi Morula. Lesi sinyathelo lwavivinywa zonke eziphilayo ezinamangqamuzana amaningi ukuthi ukukhiqiza kabusha ngokobulili ezahlukene kuphela inqubo cell division (osabalalayo, Bilateral, Kuvunguza).

Isici esivelele sesimiso cell division ngukutsi ayibi. Lokhu kuhilela ukwakheka kwamaseli ezinkulu omunye (iqanda) inani elikhulu amaseli encane nge cytoplasm ezimbalwa eduze nuclei.

embryonic period akugcini lapha, cabangisisa ukuthuthukiswa elandelayo esigabeni umbungu.

3. blastula (kumiswa izakhiwo ezinamangqamuzana amaningi ngesimo ibhamuza) - siqukethe ungqimba amaseli abizwa ngokuthi ama-embryonic. usayizi blastula osondela Usayizi iqanda ngakho ngesikhathi cell division, inani nuclei futhi DNA iyakhula.

4. Gastrulation - isinyathelo ukunyakaza ngamangqamuzana ombungu, okuholela kwetinhlavu ezintathu ungqimba ishidi sombungu. Lesi sigaba libhekene ukwanda zamagama amaprotheni ribosomes, kule nkathi kukhona protrusion besigxobo (vegetative) blastula ngaphakathi, izingongolo okuphambene axhunyiwe, futhi umgodi siqedwa blastula. Lokhu kudala umgodi, okuthiwa i-blastopore noma umlomo eyinhloko.

Ngakho, kudingeka torque engu gastrulation ukuthuthukiswa umbungu, kusukela embryonic period kulesigaba kunika amandla ukwakheka kwezitho zawo nezicubu nogwali izinhlelo.

Kufanele kuqashelwe, ukwakheka kwezicubu kanye nezinhlaka umbungu ngezikhathi ezihlukahlukene babe ukuzwela ezahlukene amathonya elimazayo kwemvelo, ezifana izifo, ngemisebe noma ejenti zamakhemikhali. Lezi zikhathi yozwela anda abizwa ngokuthi ezibucayi, kukhulile amathuba kwezinso asathuthuka.

Ngokwesibonelo, embryonic period kuyinto amaphuzu ezibucayi ambalwa. Ake sihlole ngokuningiliziwe:

1. Isikhathi blastula (emva kuqala amasonto amabili nje ebamba isisu) - umbungu noma efa, noma aqhubeka aguquka ngaphandle ngeziphambeko. Ngalesi sikhathi inani elikhulu kufa imibungu (40%), elaqala ukuthuthukiswa kwabo soguquko lwegciwane singalawuleka germ cells.

2. ngolwamashumi amabili ngosuku lamashumi ayisikhombisa emva kokukhulelwa - kwenkathi sengozini enkulu umbungu njengoba kokuqala wenziwe futhi ukwakha zonke izitho ezibalulekile.

3. Isikhathi se-fetus libhekene nokukhula ngokushesha i-fetus. Lapha kaningi kungaba khona ukwephulwa sokuthuthuka kuphela labo izitho, ngubani awukagcwalisi kumiswa yabo.

Ngakho, ama-embryonic period ontogenesis libhekene ukubunjwa nokuthuthukiswa kwezinhlangano umbungu by cell division, ukwakheka kwadingeka kwezicubu, kwezitho izinhlelo. eziphilayo ezihlukahlukene ayifani kule nkathi yesikhathi, kodwa noma kunjalo, ke kuqala lapho owesifazane ebamba futhi iphela ukuzalwa impilo entsha.