YaDROChA, nukleol, yak nav qismaki khurdro guyand, ki dar dokhili yadroi organizmhoi zukarioti mavjud ast. Ya. asosan az ribonukleoproteidho (RNP) iborat meboshad. Miqdori Ya. 1—3, bazan yakchandto-, mas., dar yadroi amyoba, reshapoyhoi gushmohidor, tukhmhujayrai baze jonvaroni muhrador (ba nom Ya.-honkanori) ast. Ya. bazan az du qismi gunogunrang iborat ast. Morfelogiyai Ya. ba vazi funksionalii hujayra vobasta meboshad. Ya. i torhoi dokhiliyadrochagii khromatin (kislotai dezoksiribonukleat -KDN dorad), zonai fibrillaho khud nakhchahoi RNP (gafsiash 5— 10 nm) va zonai granulaho 8 khud donachahoi RNP (andozaash 15—20 nm) iborat ast. Dar genhoi khpomatini dokhili Ya. molekulahoi kislotai ribonukleat (KRN)-i toribosomi sintez meshavand. In molekulaho bad ba molekulahoi KRN (bo safedaho payvast shuda, donachaho hosil mekunand) tajziya meshavand.