mi·cro·nu·cle·us 
(mī′krō-nklē-əs, -ny-)
(mī′krō-nklē-əs, -ny-)n. pl. mi·cro·nu·cle·i (-klē-ī′) or mi·cro·nu·cle·us·es
The smaller of two nuclei in ciliate protozoans that contains genetic material and functions in reproduction.
mi′cro·nucle·ar adj.