A continuous culture in which inflow of fresh medium is balanced by outflow of a corresponding volume of culture. Cells are constantly washed out with the outflowing liquid. In a steady state, the rate of cell wash-out equals the rate of formation of new cells in the system. This term is often used when, after the sequence of a DNA fragment has been determined, the function of the encoded protein is not known. An operation or procedure that can be carried out to define or delimit something.
Opine synthesis is a unique characteristic of tumour cells.
OPU See ovum pickup. ORF See open reading frame. A tissue or group of tissues that constitute a morphologically and functionally distinct part of an organism. The aseptic culture of complete living organs of animals and plants outside the body in a suitable culture medium. Animal organs must be small enough to allow the nutrients in the culture medium to penetrate all the cells.