Izizathu zokuzalwa kwamawele

Emakhulwini eminyaka adlule edlule, ukuzalwa kwamantombazane amabili noma ngaphezulu okuvela kwabesifazane kwakubhekwa njengento engavamile, kodwa namuhla odokotela bathole le nkcazelo izincazelo eziningi.

Izizathu zokuzalwa kwamawele zingaba kanje:

1. Heredity, ngoba ngamacala angu-10% amantombazane anjalo avela kulawo mindeni lapho amawele asevele ezalwa khona. Kulesi simo, konke kungachazwa ngokufaka izakhi zofuzo, njengoba owesifazane enza inani elikhulu lamahomoni, okukhuthaza ukuvuthwa kwamaqanda amaningana ngesikhathi esisodwa, ngaleyo ndlela kwandisa amathuba okukhulelwa kwezinsana ngesikhathi esisodwa.
2. Ukuqedwa kwemithi yokwelapha ngomlomo evimbela ukuvuthwa kanye nokuvuthwa kwenyanga kwamaseli wesifazane kuvame ukuholela ekukhululweni kwamaseli amaningana ngesikhathi esisodwa, ikakhulukazi ngenyanga yokuqala, njengoba umzimba uzama "ukubamba".
3. Ukwelashwa kokungabi nalutho nezidakamizwa ezikhuthaza ukuvuthwa kwegazi, kunika umphumela ofanayo.
4. Uma usebenzisa i-in vitro fertilization, ngokuvamile abesifazane "batshalwa" ama-embryo amaningana ngesikhathi esisodwa ukwenyusa amathuba okukhulelwa, futhi kwenzeka ukuthi konke noma eziningi zalezi zimbungu ziqala ukuthuthukisa ngempumelelo esibelethweni.
5. Izici ezingokwemvelo zomama, ikakhulukazi, ukuxhuma kwesisu, kungaholela ekukhulelweni kwamawele.
6. Ubudala bomama, njengoba esemdala, ithuba elikhulu lokubeletha amawele.
7. Ukulethwa okuphindaphindiwe, njengoba ukukhulelwa okusha njalo kungabangela ukuzalwa kwamawele. Uma owesifazane esevele esekhiqize abantwana ababili, lokhu kungenzeka ukuthi kabili.

Ngaphezu kwalokho, ucwaningo lubonisa ukuthi phakathi nezinkathi zezimpi nokuhlukunyezwa kwezenhlalakahle, ukuvama kokuzalwa kwalabo bantwana kuyanda. Leli qiniso alitholi incazelo, futhi ososayensi bangacabanga nje ukuthi indlela yokugcina umdabu wesintu isebenza ngale ndlela.

Kungaphawulwa ukuthi zonke izizathu ezingenhla zenza kube lula ukuchaza ukuthi kungani amawele avela - ngokungafani nezingane, ngezinye izikhathi ngisho nangamaqembu ahlukene wesini. Ngesikhathi esifanayo, isayensi asikwazi ukuchaza ukuthi kungani izingane ezizalwa ngokuphelele zizalwa (amawele weqiniso).

Ayini amawele?

Ngakho-ke, ngokukhohliswa kwendawo yonke, izingane azibheki njalo njengamaconsi amabili amanzi. I-Gemini ingaba yilapho i-dizygotic ne-monozygotic, ehluke komunye nomunye ngendlela yokukhulelwa.

Izinsana ezidakayo zizalwa lapho amaqanda amaningana ekhulelwa ngesikhathi esifanayo nge-spermatozoa ehlukene, ngakho-ke angaphandle ahluke ngokuphelele futhi angase abe nezocansi ezahlukene.

Izimbangela zokuvela kwamaphanga ama-monozygotic (afanayo) zilandelayo: isisodwa esisodwa sikhulelwe umuthi owodwa, kodwa emva kwesikhathi (kusukela ezinsukwini ezimbili ukuya kwezingu-12) i-zygote yahlukana yaba imibungu emibili (futhi ngezinye izikhathi ngisho nangaphezulu). Yingakho lezi zinsana zihlala zifana njalo, zombili izakhi zofuzo, ngaphandle, kanye nobulili. Odokotela babona iphethini elithakazelisayo, okuyinto equkethe ukuthi ekuqaleni ukuhlukaniswa kwe-zygote kuqala, okungavamile kuzoba izingane ezingenalnoyaytsevyh.

Amawele e-Siamese nezizathu zokubukeka kwazo

Isizathu sokuzalwa kwamawele e-Siamese yilokhu okulandelayo: uma iqanda elilodwa lihlanganiswa ne-spermatozoon eyodwa futhi kamuva, sekwephuzile (ngemuva kwelanga leshumi nambili emva kokukhulelwa) lihlukaniswe laba izingxenye ezimbili, kwenzeka ukuthi imibungu ayinaso isikhathi sokuhlukana ngokuphelele, eseqale ukuthuthukiswa komuntu ngamunye. Kulokhu, bahlala banamathela komunye nomunye noma ingxenye ethile yomzimba (lokhu kungaba yinhloko ejwayelekile, isisu, izitho, ubuso).