Nutfa (ar. — mani), spermatozoid (az yunoni. sperma, spermn- t-os — tukhm, zoon — mavjudoti zinda va eidos — namud), khujayrai jinsii mard, narinai hayvonot va bisyor rastaviho. Nutfa az sarak, ki yadro va khromatin dorad, gardancha va dumcha iborat ast. Dumchai Nutfa vazifai harakatro ijro mekunad. Nutfai baze bemuhraho (masalan, baze kharchangshaklho, kanaho va gayra) dumcha nadorad.
Binobar in harakati onho ba harakati amyoba monand ast. Nutfa dar tukhmhoi dar prosessi spermatogenez hosil meshavad. Hosilshavii Nutfai odam az davri ba balogat rasidan (14— 15-solagi) to pironsoli davom mekunad. Nutfai rastaniho (anterozoidho) dar anteridiy hosil meshavad. Anterozoidho du va yo yakchand dumcha dorand (masalan, dar obsabzhoi sabzu bur, baze ushnakho, sarkhas, chilband, munmuna va gayra) yo tamoman bedumcha meshavand (masalan, dar aksari rasta- nihoi tukhmdor).