Embryogenesis, visualization and migration of primordial germ cells in tench (Tinca tinca)

Embryonic and larval development of the tench, Tinca tinca, is described, along with the origin and migration routes of germ cell lineage. Primordial germ cells (PGCs) potentially transmit genetic information to the next generation, and represent a powerful tool for creating a germ-line chimera within fish species. PGCs were identified by injecting synthesized mRNA, combining green fluorescent protein and the zebrafish nos1 3UTR, under the blastodisc of embryos at the 1-4 cell stage. Developmental stages were divided into five periods defined by morphological features: cleavage (40min-5h post-fertilization (hpf), blastula (3.6-12hpf), gastrula (12-20hpf), segmentation (20-65hpf), and hatching (65-188hpf). The migration pathways of fluorescent PGCs were detected from 100% epiboly (18hpf) to the end of the hatching period (184hpf) in 69.3% of injected embryos, which migrated to the site of future gonads. Each hatching larva possessed 3-10 labeled PGCs with 95.1% of these cells localized at the genital ridge. These data may have use in practical aquaculture as well as in research to investigate germ-line chimerism in tench.