The invention provides a method of introducing a sterilized product into a controlled environment. The sterilized product is enclosed in a substantially hermetically sealed first layer, which is enclosed in a substantially hermetically sealed second layer, which is enclosed in a substantially hermetically sealed third layer, which is enclosed in a substantially hermetically sealed fourth layer. The method includes removing the fourth layer in a first environment (having a first sterility), removing the third layer in a controlled second environment (having a predetermined second sterility that is higher than the first sterility), removing the second layer in a controlled third environment (having a predetermined third sterility that is higher than the second sterility), and removing the first layer in a controlled fourth environment (with a predetermined fourth sterility that is higher than the third sterility) to expose the sterilized product.