Tuxumdonda urug'lanish jarayoni sodir bo'lganidan so'ng tuxum hujayra bachadon.,-■ nayiga o'tib, rivojlanishni davom ettiradi

(v18-1-566) Daun sindromining rivojlanish sabablarini ko'rsating.

1. 
   spermatogenezning yetilish zonasida
   

1. 
   meyozda bitta qutbga 2 ta 21 xromosoma tortiladi va 23 ta autosomali spermatozoid normal tuxum hujayrani urug'lantiradi
   

2. 
   spermatogenezning yetilish zonasida
   

2. 
   meyozda bitta qutbga 21 xromosoma tortiladi va 22 autosomali spermatozoid normal tuxum hujayrani urug'lantiradi
   

3. 
   spermatogenezning yetilish zonasida DNK reduplikasiyasi sodir bo'ladi va hosil bo'lgan spermatozoidlarning bittasi normal tuxum hujayra bilan qo'shiladi
   
4. 
   interkenez jarayonida DNK reduplikasiyasi sodir bo'ladi, spermatogenezning yetilish zonasida II meyozda bitta polyusga 21
   

ta xromosoma tortiladi va hosil bo'lgan spermatozoid tuxum hujayrani urug'lantiradi

77.