A contractile ring forms at the PGC lobe neck. (a–a’’) Time-lapse stills showing steps of PGC lobe formation Top: Corresponding embryonic stages and orientations are shown (PGC nuclei are blue). (b and b’) Aspect ratios of seven PGCs at the times corresponding to panels a and a’. (c) Cytokinetic furrow showing contractile ring components and regulators. (d) Schematic illustrating starting and ending points for cortical intensity traces. Pink arrows indicate lobe necks; dashed black line with arrowhead indicates starting and stopping points for traces. (e–j) Colocalization of the indicated proteins at the lobe contractile ring (arrowheads); pink arrows indicate lobe neck position in intensity traces. (k–l’) F-actin detected with Moesin-GFP^PGC before and after lobe formation. (m) Cortical intensity trace of F-actin^PGC from the image shown in l’; pink arrows indicate lobe neck position. Dashed white line indicates outline of PGC, * indicates nuclear position, and L indicates the lobe. Scale bar, 5 µm.