Single-cell atlas of the mandarin fish ovary reveals the trajectories of oogenesis and its immune microenvironment development

Abstract

The establishment of the immune microenvironment during oogenesis in teleosts plays a critical role in individual resistance to disease and consequently on population dynamics. However, the maternal influence on offspring immunity is poorly understood, particularly regarding the dynamic development and underlying mechanisms of the oocyte immune microenvironment. Here, we characterized the single-cell atlas of the mandarin fish (Siniperca chuatsi) ovary at late stage IV and identified three types of germ cells and five types of somatic cells. The distinctive features of the three germ cell types were further explored through enrichment analysis, suggesting that the immune microenvironment of fish oocytes is formed during the mature oocyte stage. Subsequently, based on the pseudotemporal analysis of these three germ cells, as well as clustering analysis and cell-cell communication analysis, we characterized the trajectories of oogenesis and formation of its immune microenvironment in the mandarin fish ovary. Notably, we identified a high-low-high expression pattern in immune-related pathways across different development stages of oocytes. Furthermore, the spatiotemporal expression dynamics of six key markers were validated using RNA-FISH. These findings provide novel insights into oogenesis and the establishment of maternal/innate immunity in teleost fishes.