As the precursors to gametes, primordial germ cells (PGCs) hold the unique and important role of carrying genetic information into the next generation. These cells are therefore essential to species’ reproduction and survival, and in mammals they are one of the first cell types specified within the developing embryo. PGC specification and migration has been studied across numerous eutherian mammals, birds and fish, allowing subsequent manipulation including isolation, transplantation, and gene editing. However, research in marsupials is far more limited, with in-depth investigation largely restricted to one species, the tammar wallaby. Marsupials offer an ideal system for studying PGC development due to their altricial birth, where many development processes occur postnatally, including PGC migration.
In this study, we used the fat-tailed dunnart (Sminthopsis crassicaudata) as a laboratory-based model to investigate the characteristics and migration of PGCs in perinatal young through histological and immunofluorescent staining. We found that dunnart PGCs can be detected within gonadal ridges by approximately 2 days postpartum (pp) and could be identified by the pluripotency marker POU5F1. The germ cells retained POU5F1 expression in all stages examined, and other markers are currently being characterised. Preliminary results suggest that PGC migration occurs through the hindgut in the fat-tailed dunnart, similar to many eutherian mammals, and some marsupials. However this is in contrast to the described migratory path of PGCs in the tammar wallaby, where they are reported to move primarily through the dorsal mesentery.
This work lays foundations for a deeper understanding of PGC development and migration in marsupials, and the diversity that may exist between clades. It will also provide the basis for future isolation, transcriptomic analysis and manipulation of PGCs in dunnarts and marsupials more broadly for application in conservation initiatives.