The production of sperm -- otherwise known as spermatogenesis -- generates more than 1,000 sperm per second in normal males. This productivity comes, in part, from a special cell type called the spermatogonial stem cell. The staying power of this stem cell has allowed many celebrities, including Robert DeNiro and Pablo Picasso, to father children after the age of 65.
Ukukhiqizwa kwesidoda – okubuye kwaziwe nge-spermatogenesis – kukhiqiza isidoda esingaphezu kwesingu-1,000 ngomzuzwana kwabesilisa abavamile. Lokhu kukhiqizaa, kokunye, kuvela ohlotsheni olukhethekile lwengqamuzana ekhethekile ebizwa ngokuthi inqamuzana ye-spermatogonial ye-stem. Amandla okuzinza ale ngqamuzana ye-stem asenze abaningi bosaziwayo, kuhlanganise no-Robert DeNiro no-Pablo Picasso bakwazi ukuzalisa sebeve eminyakeni engu-65.  