Manipulation of cotton fiber producing cells in cell or tissue culture offers several technical advantages for studying molecular aspects of fiber development. Length analysis of cells produced in cell and ovule culture by a fiber development mutant suggested that elongating cells produced in cell suspension culture are related to in plant fibers. Timing of some biochemical events associated with fiber development in the cell culture systems as compared to in planta has been compared in two ways. First, analysis of protein synthesis patterns indicate several similarities between ovule cultures and in planta fibers. Second, x-ray diffraction analysis of cellulose purified from several developmental stages of in vitro and in planta fibers showed that while crystalline cellulose is produced by suspension culture cells, the diffraction pattern is most similar to cellulose from immature in planta fibers.