Yiziphi izici zesakhiwo samaseli wesilisa wesilisa?
Ngakho-ke, i-spermatozoa, ngenxa yokuthi kufanele ibe nokuhamba okuphezulu kokufaka umquba, kukhona amangqamuzana amancane, omzimba wakhe ohlangene. I-sperm, ngokungafani ne-ovum, ayinayo i-cytoplasm eningi. Iqukethe ingxenye ephethe i-nucleus ebizwa ngokuthi ikhanda, ne-flagellum (umsila), okuyisigungu sayo sokunyakaza. Kusukela ezinhlobonhlobo okuthiwa i-subcellular ku-spermatozoon, kune-mitochondria ewuhlinzeka ngamandla adingekayo ukunyakaza, i-acrosomal vacuole (equkethe ama-enzyme wokuqothula ama-efufusimu weqanda elivuthiwe), i-centriole eseduze. Ubude obuphelele be-spermatozoon buphakathi kwama-60 μm, lapho umsila ungama-55 μm.
Uma ushiya isisindo somzimba wesilisa, isilwane, isidoda singasanda kuzalwa, isb. abanakho ukuhamba, kodwa basungulwa ngokuphelele ngokomzimba. Ngakho-ke, abanalo ikhono lokutshala. Ukusebenza kwamaseli wesilisa wesilisa kwenzeka ohlelweni lwe-vas deferens.
Yiziphi izici zaleso sakhiwo eziyisici se-germ cell cell?
I-germ cell yesifazane, iqanda, ngokungafani ne-spermatozoon, isayizi enkulu kakhulu futhi ayikwazi ukuhamba. Ubukhulu bayo bufinyelela amamitha ayi-100-200 kubantu. Lokhu kuyingxenye ngenxa yokuthi yiqanda eligcinwa ukuxhumeka kwe-trophic, okuvele kudingekile ekuthuthukiseni umbungu ngesikhathi sokuqala. Futhi, inqwaba yezakhiwo ze-cytoplasmic ekubunjweni kwayo ziyadingeka ekwakheni izizukulwane zokuqala zamaseli embryonic - blastomeres.
I-egg cell, ngokuphambene ne-spermatozoon, ibonakala nge-nucleus enkulu eyindilinga, lapho i-euchromatin (i-nucleoprotein eyakhelwe khona eduze nendawo ye-nucleus, ephoswe kakhulu, eyabangela ukudluliselwa kolwazi lwezofuzo) inamandla futhi iqukethe inani elikhulu le-cytoplasm. Ngesikhathi esifanayo i-mitochondria iningi elincane, elibangelwa ukuhamba okuncane kwamangqamuzana omzimba wesifazane. Kumele futhi kuqaphele ukuthi amangqamuzana omzimba wesifazane angabodwa. Kungenzeka ukuthi, mhlawumbe, isigaba sokuqala sokubunjwa kwabo, esiteji se-ogony. Ngokujwayelekile, ama-ovules asondelene kakhulu namaseli angama-somatic, eqinisweni, ahlanganisa ulwelwesi oluxhunyiwe nolwe-epithelial emhlabeni wonke wesifazane wesifazane ocansi. Le nkimbinkimbi yayibizwa ngokuthi i-ovarian follicle. Isakhiwo saso siyinkimbinkimbi ekwenzeni i- oogenesis .
Zonke umehluko weqanda ezivela kumdlwane azikwazi ukufakwa etafuleni elilodwa, ngakho-ke lezi zingqamuzana ezimbili ezahlukene.
Yiziphi umehluko omkhulu phakathi kwama-germ cells?
Ukutshela ngalokho amaqanda ahluke khona nge-spermatozoa futhi kungani, ngokuqhathanisa phezulu, ngingathanda ukubhala umehluko wabo oyinhloko. Phakathi kwabo kukhona:
- isethi ye-chromosome (ku-spermatozoa - i-chromosome ye-X, kuma-oocyte - U);
- i-nuclear-cytoplasmic ratio ephezulu (ephezulu ku-spermatozoon, ephansi eqanda);
- ubukhulu nokuma (okukhulu futhi okuhlanganyelwe ngokumelene nezincane futhi ezihlangene);
- i-sperm ine-organ organ.
Ngakho-ke, kungashiwo ukuthi umehluko omkhulu we-spermatozoon ovela eqandeni usesakhiwo, ngenxa yenani lezinto eziphilayo elinikezwe zona.