Abstract: An apparatus and method for the in vitro culturing of animal cells, e.g., mammalian cells, to attain mass growth of the cells per se and/or to recover cell-secreted products of interest therefrom, in which an integral culture and gassing element is formed from spirally-wound or concentricallywrapped lengths of a liquid-impermeable, oxygen-permeable membrane envelope such that narrow cell culture spaces are formed between adjacent windings or wrapping of the envelope. Cells in the culture spaces, which spaces may optionally contain cell substrate material, are cultured in contact with a culture medium introduced into the spaces from an end of the element, and in contact with oxygen-containing gas supplied to the membrane envelope for diffusion across its oxygen-permeable walls into the culture spaces.