Temporal and spatial localization of three germline-specific proteins in medaka

We show that germline-specific proteins, olvas (vasa), nanos, and tdrd1 (tudor), alter their localization in the cytoplasm during germline development in the medaka (Oryzias latipes). By immunohistochemical analysis, these three germline-specific proteins were detectable on granule-like structures in the cytoplasm of migrating primordial germ cells. In the germ cells of the gonadal primordia, these granules formed a hollow area lacking these three protein components. During the sexual differentiation of the female gonads, the granules were found to be reduced in size in the germ cells undergoing cystic division and they showed a perinuclear localization in the oocytes. However, the germ cells in the male gonads retained their hollow granules during this early sex differentiation stage. We further demonstrate the differential localization of olvas, nanos, and tdrd1 on these granules during medaka germline development.