Germline

In biology and genetics, the germline of a mature or developing individual organism is the subset of cells which either are capable of being passed to an offspring--such as the sex cells--or belong to the lineage from which these cells directly descend, such as the gametocyte and the stem cells from which the gametocytes derive. Mutations or other genetic changes arising in the germline are liable to be passed to offspring, while those arising in non-germline somatic cells are not.

"Germline" can also be used to refer to a lineage of cells spanning many individuals; for example, the germline that links any living individual to the hypothesized first eukaryote of about one billion years ago, from which all plants and animals descend.