Abstract: In many fishes,germ cells originate from primordial germ cells (PGCs) and are segregated from somatic cell lineage during embryogenesis.Dead end (dnd),a maternal gene,is exclusively expressed in PGCs and encodes an evolutionary conserved RNA-binding protein,playing a critical role in germline cell development during embryogenesis.In this study,according to the nucleotide sequences of dnd from large yellow croaker (Larimichthys crocea) in NCBI database,partial cDNA sequence was cloned by PCR and denoted as Lcdnd. Meanwhile,we addressed the expression analysis of Lcdnd by means of real-time quantitative PCR (qRT-PCR) and whole mount in situ hybridization (WISH).Results showed that Lcdndspecifically expressed in gonad and expression level in ovary were significantly higher than those in testis.Results showed that the expressions of Lcdnd were detected in all stages examined during embryogenesis.Lcdnd tended to gradually decrease as the embryo developed.Furthermore,results of WISH showed that Lcdnd transcripts were localized to the cleavage furrow during early cleavage stages.As the embryo developed to blastula stage and early-gastrula stage,the increasing positive signals started to locate at a small number of cells that means the specification of future primordial germ cells.Moreover,the dnd-positive cells were mainly distributed in the mesentoderm of germ ring region at early-gastrula stage.During subsequent stages,putative increasing PGCs migrated to the embryonic shield region along the germ ring and then the dnd-positive cells increased at both sides of the trunk.At somitogenesis stage,the dnd-positive cells were distributed as two lines located in lateral mesoderm.Subsequently,those cells migrated toward the abdomen of the trunk along the dorsal-ventral axis and then clustered in the putative primitive genital ridge.In short,we successfully used Lcdnd gene as a germ cell marker for the first time to elucidate the origin and migration of PGCs of large yellow croaker, and laid the foundation for further studies on germ cell specification and development and the fertility control.