Fig. 5

Cell fusion and sub-stages. Cell-cell junctions are labeled by ajm-1::gfp (green) whereas nuclei are labeled with TdTomato::H2S (magenta). For each stage, Nomarski (left) and confocal (right) images are from the same worm, but taken separately on different microscopes. Junctions between syncytial hypodermis, vulval cells and the uterus are visible as rings, here viewed from the side. Prior to fusion of anterior and posterior vulval cells, the boundary between these cells are visible as vertical (dorsal/ventral) line of ajm-1::gfp fluorescence. In the L4.1 animal shown, vulC and vulD cells have formed toroids but have not fused. Anterior and posterior vulA cells are still migrating but have not contacted each other. In the L4.2 animal, vulA, vulC and vulD cells have fused, indicated by the absence of ajm-1::gfp fluorescence between anterior and posterior cells. In L4.1, L4.2 and L4.3 animals shown, vulE and vulF cells have not fused. However, in the L4.5 animal shown, the boundary between anterior and posterior vulF cells is not detectable, indicating cell fusion had taken place. In the L4.7 stage, further changes to the vulval cell shapes have occurred, but vulE cells have not fused yet