Utywala ngumntu onobungozi ongangena kuyo nayiphi na imithintelo yemvelo kwaye ubetyukise onke amaseli omzimba, kuquka isondo. Abantwana, abakhulelwe ngaphantsi kwefuthe lotywala, babonakaliswe ngongqondo obuncitshisiweyo kunye nokukhuseleka komzimba , kwaye ngamanye amaxesha baneengxaki ezinzima ekuphuhliseni.
Iingcali zenzululwazi ziye zafakazela impembelelo engafanelekanga yobunxila kumaqanda amabhinqa, utshwala buyakwazi ukuphazamisa ikhowudi ye-gene ye-germ cell, leyo eyakhokelela ekutheni i-trisomy okanye ezinye izifo. Ekubeni amaqanda esizayo alawulwa yintombazana e-ovari ukususela ekuzalweni, ngoko konke ukutywala kotywala kunokuchaphazela umntwana.
Ukusela utywala ngaphambi kokucwangcisa ukukhulelwa, umfazi usengozini "ukutyhefuza" ezinye zeentolli ezinokuthi zithwale izinto ezinobuthi. Kodwa ngenxa yemithetho ye-physiology, iifollic zempilo zilula kwaye zimele kuqala kumgca wokuvuthwa, kunye neeseli ezichaphazelekayo zihla kwaye zikhule emva kweminyaka engama-30. Ngoko ke, ukuthatha utywala ebusheni ngaphambi kokucwangcisa abantwana, kukho ithuba eliphezulu lokubeletha umntwana ongenakulungile kwikamva.
Impembelelo engebiyo yotywala kwiqanda ngenyanga yokukhulelwa komntwana, okokuthi. ukuthatha iziyobisi ezinxilisayo ukususela kumhla wokuqala wokuhamba kwimihla , umfazi angabangela ingozi engenakucatshangelwa kwintsana ekhulelwe kwiqanda kule nyanga. Impembelelo yotywala kwiqanda ikhokelela ekutshatyalalisweni kweekhonkco ezithile kwi-genetic code of cell, ekutshintsheni kwindlela yokwenziwa kweprotheni. Umthombo wezondlo kwixesha elizayo umntwana.
Ukuba isalathisi esichumayo isilungelelaniswa ukuvelisa amawele afanayo, umphumo ongeyiphumo wokusela utywala ekukhulelweni kukukhokelela ekuzalweni kwamawele e-Siamese.
Kuyaziwa ngemiphumo emibi yotywala kwi-sperm ekukhulelweni komntwana. Utywala izinto zenza "ngokuvuyisayo" kwiiseli zesilisa, i. ukwandisa umsebenzi wabo, kodwa ngexesha elifanayo ukutshabalalisa ulwazi lofuzo. Ngaloo nto kuvela ukuba "i-spermatozoa" inetyhefu ingafikelela ngokukhawuleza kwaye iqule iqanda, kunokuba iiseli zesilisa ezinempilo. Le nkqubo iphikisana nemithetho ye-physiology, phantsi kweemeko apho i-spermatozoa ebuthakathaka ethwele i-RNA ephosakeleyo ayisebenzelanga ngaphaya kune "abazalwana" abanempilo.
Umphumo wobutywala ngexesha lokukhulelwa
Ukusetyenziswa kotywala ngexesha lokukhulelwa, umfazi ubangela ingozi engenakulinganiswa nengane yakhe.
Umphumo onobungozi wobutywala ekuphuculeni umtsalane awuphepheki, ekubeni utshwala lula ngokungena kwi-barrier. Ixesha eliyingozi kakhulu li-6-8 kunye nee-12-14 iiveki, ngelo xesha izigaba ezisemgangathweni zokubunjwa kwe-fetal zenzeka.
Iglasi lewayini elixiliswe kwiiveki ezi-1-2 zokukhulelwa aziyi kuba nemiphumo emibi, ngenxa yokuba Ngethuba lexesha, umntwana okhulelweyo uyahamba ecaleni kwimizi yesibindi ukuya kwisibeleko kwaye akafumani isondlo esivela kumama.