Visualisation of germarium cells in semi-thin and ultra-thin sections. A, B, longitudinal semi-thin sections of germaria stained with methylene blue. C, D, ultrastructure of cyst cells from the uninfected and the wMelPop-infected flies. Arrows point to bacteria; arrowheads denote ring canals between neighboring cells. Scale bars correspond to 10 μm (A, B) and 2 μm (C, D), respectively.