Dual-flow jet engine having a longitudinal axis and comprising an engine and a nacelle surrounding the engine which comprises a fan casing, in which a stream of a bypass flow is delimited between the nacelle and the engine and in which an air stream circulates in a direction of flow, said nacelle comprising: - a fixed structure fixed to the fan casing, - a movable assembly having a movable cowl, and the movable assembly comprises a slide to which the movable cowl is fixed, the slide being movable in translation on the fixed structure in a direction of translation between an advanced position in which the slide is positioned in such a way that the movable cowl is close to the fan casing and a retracted position in which the slide is positioned in such a way that the movable cowl is away from the fan casing to define between them an open window between the stream and the outside of the nacelle, and the nacelle further comprises: - a plurality of blades each comprising a first end mounted to be movable in rotation on the slide about an axis of rotation that is overall parallel to the longitudinal axis, in which each blade is movable between a stowed position in which the blade is outside of the stream and a deployed position in which the blade is across the stream, in which said plurality of blades is divided up into groups, in which each group comprises a first blade situated furthest downstream with respect to the direction of flow with respect to the other blades of the same group, in which, for each group, the blade of a rank 'n' is situated upstream with respect to the blade of rank 'n-1' in the direction of flow and is offset angularly about the longitudinal axis X with respect to the blade of rank 'n-1', - a set of actuators ensuring the displacement of the slide between the advanced position and the retracted position, and vice versa, and - a manoeuvring system intended to displace each blade from the stowed position to the deployed position and vice versa, in which the manoeuvring system comprises: - a cam integral to the first blade of one of the groups and having a tooth, - a groove integral to the fixed structure in which the tooth is housed and in which, during the displacement of the movable assembly, the tooth follows the groove and rotationally displaces said first blade, - a first transmission system which transmits the displacement of the first blade bearing the cam to a first blade of each other group, and - for each group, a second transmission system which transmits the displacement of the blade bearing the cam or displaced by the first transmission system to each of the other blades of said group. - a fixed structure fixed to the fan casing, - a movable assembly having a movable cowl, - a plurality of blades each comprising a first end mounted to be movable in rotation on the slide about an axis of rotation that is overall parallel to the longitudinal axis, in which each blade is movable between a stowed position in which the blade is outside of the stream and a deployed position in which the blade is across the stream, in which said plurality of blades is divided up into groups, in which each group comprises a first blade situated furthest downstream with respect to the direction of flow with respect to the other blades of the same group, in which, for each group, the blade of a rank 'n' is situated upstream with respect to the blade of rank 'n-1' in the direction of flow and is offset angularly about the longitudinal axis X with respect to the blade of rank 'n-1', - a set of actuators ensuring the displacement of the slide between the advanced position and the retracted position, and vice versa, and - a manoeuvring system intended to displace each blade from the stowed position to the deployed position and vice versa, in which the manoeuvring system comprises: - a cam integral to the first blade of one of the groups and having a tooth, - a groove integral to the fixed structure in which the tooth is housed and in which, during the displacement of the movable assembly, the tooth follows the groove and rotationally displaces said first blade, - a first transmission system which transmits the displacement of the first blade bearing the cam to a first blade of each other group, and - for each group, a second transmission system which transmits the displacement of the blade bearing the cam or displaced by the first transmission system to each of the other blades of said group. - a cam integral to the first blade of one of the groups and having a tooth, - a groove integral to the fixed structure in which the tooth is housed and in which, during the displacement of the movable assembly, the tooth follows the groove and rotationally displaces said first blade, - a first transmission system which transmits the displacement of the first blade bearing the cam to a first blade of each other group, and - for each group, a second transmission system which transmits the displacement of the blade bearing the cam or displaced by the first transmission system to each of the other blades of said group.