Fiber optic adapter with an internal shutter assembly and integrated alignment sleeve holder

A fiber optic adapter comprising:

• a housing defining an open-ended first through-channel having a first port at a first end and a second port at a second end opposite the first end, the first and second ports being configured to receive first and second fiber optic connectors, respectively, the housing comprising an aperture opening into the first through-channel laterally;
• a cover comprising a cylinder with a bore;
• an alignment sleeve positioned inside the bore, the alignment sleeve comprising an open-ended second through-channel configured to receive a first ferrule of the first fiber optic connector and a second ferrule of the second fiber optic connector, the cover positioning the cylinder inside the first through-channel, the cover comprising a closure portion that closes the aperture of the housing;
• a shutter door adjacent the first port, the shutter door being movable between an open position and a closed position;
• and
• a biasing member configured to bias the shutter door toward the closed position, the shutter door being configured to be automatically transitioned to the open position when the first fiber optic connector is inserted into the first port and to be automatically transitioned to the closed position by the biasing member when the first fiber optic connector is removed from the first port.