Umanyolo ubhekisela enkambisweni yokuhlanganiswa kwamaseli wesilisa nabesilisa besilisa (isisu neqanda), okuholela ekuzalweni kokuphila okusha. Ukutshala izihlahla ze-ovum, i-excreta, izimpawu zokukhulelwa zifundwa.
Isibungu
Ekupheleni kwesenzo socansi, isilwane esivela emzimbeni wesilisa wesidumbu sidlula emgodini wesibindi. Emlonyeni wesibeletho, isidoda sondliwa emkhakheni we-alkali we-mucus womlomo wesibeletho. Bese beqhubeka nokunyakaza kwabo, bangene emathinini amathanga (ama-fallopian). Ibanga elidlula insimu lingama-20 cm kuphela, kodwa ngokucabangela ubukhulu besitembu lesilisa lokuzala, kungathatha amahora amabili ukunqoba le ndlela.
Umzabalazo wokusinda
Ngokukhishwa kwe-ejaculation cishe kukhululwa izigidi ezingu-300 ze-spermatozoa, kodwa ingxenye encane (cishe abayizinkulungwane ezingu-10) ifinyelela ku-tube fallopian lapho iqanda likhona khona. Ngaphansi kwalokho itholakala ngokuqondile neqanda. Ingxenye ebalulekile ye-spermatozoa ibhujiswe emvelweni onobuciko obunzima besifazane, futhi ihlakazekile ezingxenyeni ezihlukahlukene zegciwane lesisu. I-spermatozoons ithola ikhono lokutshala, kuphela emva kokuchitha isikhathi esithile emzimbeni wesifazane. I-fluid fluid yegciwane lesigciwane ivuselela i-spermatozoa, okwenza ukunyakaza okungahambi kahle kwemisila yabo ibe namandla. Ukuhamba kwendoda kuze kube yilapho kutholakala khona ukubeletha kuhlinzekwa ukunyakaza kwezivumelwano zesisu. I-Prostaglandins equkethwe uketshezi lwesimila, kanye ne-excited in orgasm yabesifazane, ivuse lezi zincintiswano.
I-Ovum
Ngemuva kokuphuma ku-follicle ngesikhathi sokuvuthwa, iqanda liyaphuma ngaphandle kwesigcawu se-uterine ngokunyakaza okufana namagagasi amangqamuzana agqoke ithubhu le-fallopian. I-fusion yeqanda ne-spermatozoon ngokuvamile ivela engxenyeni yangaphandle ye-tube ye-uterine cishe amahora amabili emva kocansi. Endleleni eya esitokisini seqanda ngaphansi kwethonya lemfihlo yecala lomzimba wesifazane, i-spermatozoa ilahlekelwa yi-cholesterol yayo, eyanciphisa izibilini zazo ze-acrosomal. Le nqubo ibizwa ngokuthi i-calacitation - ngaphandle kokuthi ukukhulelwa akunakwenzeka. Ngesinye isikhathi esiseduze neqanda, i-spermatozoon isetshenziswe "ngamakhemikhali" kuwo. Uma uxhumane ne-spermatozoa ebusweni be-oocyte, izibilini zazo ze-acrosomal zibhujiswa ngokuphelele, futhi okuqukethwe kwe-acrosome ngayinye (i-enzyme ene-sperm cell) ishiya imvelo.
Ukungena
Ama-enzyme e-isolated e-isolation abhubhisa izakhi zokuzivikela zeqanda - i-cumulus mass kanye negobolondo elimnyama. Ukwakha umgodi okwanele ukungena ku-spermatozoon eyodwa, kudingeke ukuthi kukhishwe ukukhishwa kwesikhumba okungenani amahektare angama-100. Ngakho-ke, iningi le-spermatozoa elifinyelela ku-oocyte "ukuzidela ngokwabo" ukuze lisethe esinye isidoda ku-cytoplasm yayo. Ngemuva kokusungulwa kwe-spermatozoon emaqanda, ukuhlanganiswa kwezidalwa zabo zofuzo kwenzeka. I-zygote eholayo iqala ukuhlukanisa, ivulele umbungu.
Ngokushesha ngemva kokungena kwesibindi emaqanda, kukhishwa ukwenziwa kwamakhemikhali, okwenza kungenakwenzeka kwezinye izidakamizwa.
Isigaba sesibili se-meiosis
Ukungena kwe-nucleus ye-spermatozoon eqenjini kuba isibonakaliso sokuqedwa kwesigaba sokunciphisa okwesibili (isigaba sesibili se-meiosis) esaqala ngesikhathi se-ovulation. Lokhu kwakha i-ostida ye-galloid kanye nomzimba wesibili we-polar (okuyinto elandela izinqubo eziguqukayo). Khona-ke i-nuclei ye-spermatozoon ne-ovum ihlanganisa ukwakha i-zygote ye-diploid equkethe izakhi zofuzo zabazali bobabili abazali.
Ukwakha phansi
Ubulili bezingane ezizayo buvezwa kakade esigabeni sokukhulelwa. Okuzoba yiyo, kuxhomeke kuphela kulesidoda. Ubulili besisu buxhomeke ekubeni khona kwe-X noma Y chromosome. Kusukela kumama, umfanyana uthola i-X kuphela ye-chromosome, kanti kusukela kubaba ingathola kokubili ama-chromosomes e-X-no-Y. Ngakho-ke, uma iqanda lihlwanyelwa isidakamizwa equkethe i-chromosome ye-X, i-fetus yesifazane iqala (46, XX), ne-fetus yesilisa (46, i-XY) uma ifakwe ku-spermatozoon ene-Y chromosome.
Ukuhlukaniswa kweselula
Ngemva kwamahora ambalwa emva kokukhulelwa, ukuhlukana kwamamitha amaningi kwenzeka ku-zygote, okuholela ekusungulweni kwe-conglomerate yamaseli abizwa ngokuthi i-morula. Amaseli e-Morula ahlukanisa wonke amahora angu-12-15, ngenxa yalokho aphendukela kuba yi-blastocyst, equkethe amangqamuzana angaba ngu-100. I-Blastocyst ikhiqiza i-hormone ebizwa ngokuthi i-chorionic gonadotropin, okuvimbela ukuzenzekelayo kwe-progesterone yomzimba ophuzi. Cishe ngemva kwezinsuku ezintathu emva kokukhulelwa, i-blastocyst iqala ukuhamba eduze kwebhubhisi ye-fallopian ibe yindawo yomzimba. Ngaphansi kwezimo ezijwayelekile, wayengenakunqoba i-sphincter ye-tube fallopian. Kodwa-ke, ukukhiqizwa kwe progesterone ngomzimba ophuzi, okwenziwe ngemuva kokukhulelwa, kukhuthaza ukuphumula kwemisipha nokunyakaza kwe-blastocyst emgodini we-uterine. Ukulimala noma ukugqama kwesibani se-tube uterine, okuvimbela ukuqhubekela phambili kwe-blastocyst kulesi sigaba, kuholela ekuthuthukiseni ukukhulelwa kwe-ectopic, lapho umbungu uqala ukukhula ngaphakathi kwebhubhisi.
Ukukhulelwa okuningi
Ezimweni eziningi, owesifazane uneqanda elilodwa kuphela inyanga ngayinye (enye iphuma e-ovary ngayinye). Kodwa-ke, kwezinye izimo, amaqanda adonswa ngesikhathi esisodwa kusuka kokubili ama-ovari. Bangakwazi ukukhulelwa nge-spermatozoa ehlukahlukene, okuholela ekuthuthukiseni amawele e-heterozygous. Kulesi simo, i-fetus ngayinye ine-placenta ehlukile. Ngokuvamile kakhulu iqanda elikhulelwe lihlukanisa ngokuphindwe kabili, okuvela kuwo imibungu emibili ehlukene. Lokhu kuholela ekuthuthukiseni amawele afanayo, ngesethi yezinhlobo zomzimba kanye ne-placenta ejwayelekile. Ukuhlukaniswa okungaqediwe kweqanda amahora ambalwa emva kokukhulelwa kuholela ekubukeni kwamawele e-Siamese.
Ukutshalaliswa
Njengoba sesifinyelele emgodleni wesibeletho, i-blastocyst isetshenziselwa isikhumba somswakama ohlangene odongeni lwayo. I-hormone ekhishwe yi-blastocyst ivimbela ukulahlwa kwayo njengomzimba wangaphandle. Kusukela ukufakelwa okuphumelelayo kwe-blastocyst, ukukhulelwa kuqala.
Izinkinga zokuthuthukiswa
Cishe ingxenye eyodwa kwezintathu zamathambo okutshalwa kweqanda ekhulelwe ayenzeki, kanti umbungu ufa. Kodwa ngisho nokufakelwa okuphumelelayo, imibungu eminingi ineziphene zofuzo (isibonelo, i-chromosome eyengeziwe). Ukuphulwa okunjalo kuvame ukuholela ekufeni kwe-embryo ngokushesha ngemva kokufakwa. Ngezinye izikhathi lokhu kwenzeka ngaphambi kokubambezeleka kokuqala esikhathini, futhi owesifazane angase angazi ngisho nokukhulelwa okuhlulekile.