Because the germline eventually gives rise to gametes, which have the potential to become the

next generation, it is arguably one of the most important cell types and understanding how the

germline is specified and maintained throughout an organism's lifetime is a fundamental

question in biology. This dissertation investigates the underlying mechanisms of germline

specification, maintenance, and regeneration in the amphipod crustacean Parhyale hawaiensis.

First I identified additional germline markers, Ph-piwi1, Ph-piwi2, Ph-tudor, and Ph-gustavus in

Parhyale. Then I characterized the Parhyale adult germline stem cell (GSC) niche by using a

combination of molecular markers (for germline and stem cell niche components) and using cell

proliferation assays. I generated an antibody to Parhyale Vasa, which was instrumental in

confidently identifying germline cells. In the Parhyale adult ovaries, this GSC niche likely

resides within the germline ridge. Understanding where the putative GSC niche is important for

evolutionary comparisons and can give clues as to how germline regeneration occurs. Finally, I

investigate the potential role of bone morphogenetic protein (BMP) signaling in Parhyale

germline maintenance and regeneration. This study provides insight into germline specification,

the GSC niche, and adult regeneration in the amphipod crustacean, Parhyale hawaiensis.