Disclosed is a container and method for filling same. The container includes a thermally resealable portion that is fusible in response to thermal energy, and a container body having a sealed empty chamber in fluid communication with the resealable portion for receiving therein a substance. The container also includes a base, a mid-portion, and an upper portion axially spaced from the base on an opposite side of the mid-portion relative to the base. Each of the base and upper portion define a laterally-extending dimension greater than a maximum laterally-extending dimension of the mid-portion. The method of filling the container includes penetrating the resealable portion with an injection member and introducing a substance into the chamber, withdrawing the injection member while engaging the base of the body to substantially prevent axial movement of the body, and applying thermal energy to the resealable portion to thermally fuse the penetrated region thereof.