A container assembly (500) for storing a tissue sample is disclosed. The container assembly (500) comprises a container (1) and a cover. The container (1) stores a tissue sample (45) and has a bottom (13). The cover engages with the container (1). The cover comprises a top member (321), seal (22), and puncturing member (323). The top member (321) comprises a receptacle (211) which contains a preserving agent. The seal (22) seals off the receptacle (211). The puncturing member (323) breaks the seal (22) by displacement of the puncturing member (323). The container assembly (500) has first and second positions. In the first position, the container (1) is isolated from the receptacle (211). In the second position, the container (1) is in fluid communication between the receptacle (211) and the container (1). The container assembly (500) further comprises a separator (see 31, figure 9) positioned between the seal (22) and the bottom (13) of the container (1). The separator (31) is provided with at least one aperture which is adapted to provide a fluid passage between the receptacle (211) and the container (1). A method of preserving a tissue sample (45) is also disclosed.
