primordial germ cell obsolete primordial germ cell true Primitive cell type that is involved in the reproduction of the organism beginning with the sexual differentiation of the gonads at NF stage 52. In males specifically, it migrates from the genital ridge cortical region into the medullary tissue, where it forms spermatogonia. In females it is embedded in the cortical region and multiplies as oogonia. PGC UBERON:3010293 primitive germ cell