Uyini zygote, iziphi izici zayo nokuthuthukiswa

Ukuze uqonde ukuthi inqubo ukuvundisa ukuzalwa impilo entsha, kudingeka uzijwayeze imiqondo eyisisekelo. Kuyadingeka ukuba ukubhekana neqiniso lokuthi zygote ezinjalo. Futhi ukuphendula imibuzo mayelana kwakhiwa kanjani it is, okuyinto inezici ezithile, yiziphi izigaba yentuthuko yayo esiqhubekayo esingazuzisa ukuyivimbela.

Ake uqale kusukela ekuqaleni, ne Impendulo yombuzo wokuqala. Uyini zygote? Lokhu cell, ezakhiwe nokuhlanganiswa gametes ezimbili inqubo umzali othiwa kokukhulelwa. Kuyinto isici eziphilayo kwabobulili esetshenziselwa ukuzalela kubo. Ngu nezidalwa akha zygote, akuzona kuphela abantu nezilwane kodwa futhi izitshalo eziningi athile kanye nesikhunta. Leli gama liye langena isazi sezitshalo Eduard Strasburger zisuka eJalimane ngamaloli ngasekupheleni kwekhulu le-19.

Eqaphela ukuthi zygote, khumbula libhekene kuka ukwakha yezinyoni yayo. Ubulili amaseli, noma gametes, akhiqizwa yizinhlaka ezikhethekile (ubulili), basuke libhekene khona olulodwa (haploid) iqoqo chromosome. Njengoba siye waqonda, ukwakheka zygote kwenzeka ngenxa inyunyana gametes ezimbili, okusho ukuthi liqukethe double (diploid) iqoqo abathwali DNA. iseli abahlukile, futhi isishiya ephilayo entsha, nge ncazelo, ososayensi, kuyinto totipotent. Okungukuthi, ikwazi ukukhiqiza ngokuphelele noma iyiphi iseli zomzimba. Yini enye nentshisekelo kule isakhiwo cell? I zygote uhlukanisa ekuqaleni akakuthandanga yeseli njalo. Ngaphambi ukwahlukana kungekho sigaba sokukhula, futhi ngenxa yalokho ngamunye okwalandela indodakazi amaseli buzoba buncane kunalena eyedlule. Ngenxa fragmentations ngokulandelana, iqanda avundiswa uba njengamazwi berry kamalibhele.

Uma sicabanga yonke inqubo ukuthuthukiswa umbungu iyonke, kungenzeka ukuphendula umbuzo uyini zygote, kanje. Kuyinto omunye izigaba yentuthuko yayo. Isinyathelo sokuqala kulokhu kubhekwa gametes, futhi izinyathelo okwalandela ebonakala izinguquko ilandelana zygote. Nazi amazinga ngokulandelana yokuzihlukanisa kwamangqamuzana ngokwemisebenzi yawo igciwane. Ngokulandelayo, ngemva zygote esiteji - Morula (akukho ingaphakathi lichaza ekwakheni), kwalandela blastula (bungu olulodwa), i-gastrula (emithathu ungqimba bungu) Ekugcineni neurula, okuyinto kahle ludlulele organogenesis.

Phela, siphawula iphuzu elithakazelisayo: esigabeni zygote a eziphilayo kungase kahle zephuze. Lokhu kwenzeka ngo-fungus kanye ulwelwe. Ngemva ukuvundisa kumiswa yeseli diploid kuba umile futhi iqhubeka isikhathi eside. Kulokhu, iseli ngokuthi zygospore. Kubantu, isikhathi ukuphumula kuyinto amahora amathathu kuphela. Ngalesi sikhathi, i-embryo ngekusasa ihamba phakathi tube fallopian esibelethweni, lapho kwesikhathi ngeke zokwakha we esibelethweni e ulwelwesi. Ukuphazamisa ukugeleza yenqubo uqobo kanye ukuqhubeka zygote kungenzeka izici ezimbi ezifana ukuguquka kwezakhi zofuzo ezingeni zezakhi zofuzo umuntu noma ukufakela ama-chromosome lonke, utshwala owesifazane, izidakamizwa kwezidakamizwa, kunemithi noma amaphilisi owaphuzayo, ukubhema, izifo ezibangelwa amagciwane.