Abstract: Disclosed herein are flow-through apparatuses for delivering microcarriers, the apparatuses comprising a body having a fixed volume and comprising an inlet, an outlet, and a cavity configured to contain at least one microcarrier; a first seal attached to the inlet and comprising at least one inlet port; a second seal attached to the outlet and comprising at least one outlet port; and at least one conduit attached to the at least one inlet port and/or the at least one outlet port. Systems comprising such flow-through apparatuses in fluid contact with a bioreactor are also disclosed herein. Further disclosed herein are methods for delivering microcarriers into a reactor, the methods comprising placing a delivery apparatus comprising at least one microcarrier in fluid contact with the reactor; and applying a force sufficient to induce flow of the at least one microcarrier into the reactor.