The increase in interfollicular epidenmal nibosomes on the backs of mice initiated with 7,12-dimethylbenz(a)- anthracene and promoted with 12-O-tetradecanoyl-phambol

The increase in interfollicular epidenmal nibosomes on the backs of mice initiated with 7,12-dimethylbenz(a)anthracene and promoted with 12-O-tetradecanoyl-phambol 13-acetate was disproportionate to the increase in epi dermal wet weight, protein, and DNA. Whereas mibosame numbers increased fiveto sixfold 48 hr after the first, fourth , or eighth application of 12-O-tetradecanoyl-pharbal 13-acetate, epidemmaltissue increased only twoto threefold at these times. This disproportionate increase was due to the fact that, concurrent with the increased amount of inter follicular epidermal tissue and cells, nibosames per g epi dermis and per mg DNA increased two to three times non mal. The tissue concentration and cellular content of nba somes were also increased in the epidermal component of induced squamous papillamas. The work of others has demonstrated that, during growth of other tissues and on gans, nibosome accumulation is proportionate to accumu lation of tissue and/on cells. The results of our study mdi cate that the epidermis may have unique kinetics of nba some accumulation during induced growth. Furthermore, these findings suggest the interesting possibility that other tumor-prone surface epithelia, such as the linings of the respiratory and gastrointestinal tracts, have similar kinetics of nibosome accumulation during induced growth.