Method and apparatus for in vitro culture of cells in culture medium to produce a viable cell mass of cell number greater than the initial cell number, wherein a cell mass of particular cell number is cultured in a first oxygen-permeable culture sub-compartment to an increased cell number, and then aseptically transferred directly from the first sub-compartment to a next serial culture sub-compartment providing additional medium and/or culture space for further growth and reproduction to produce a viable cell mass of still higher cell number. Continued transfers are made, if necessary, to successive serial culture sub-compartment until a viable cell mass of desired cell number is attained, particularly one useful for seeding of a production-scale culture system.
