Tissue-Specific Inhibition of Cell Proliferation in Embryonic Stomach Epithelium in Vitro

Initial evidence is presented which supports the possibility of a tissue-specific inhibitory feedback control of cell proliferation in developing stomach mucosa. Cell proliferation in 203 explants of embryonic chick stomach, intestine, and skin was assayed, using vinblastine arrest techniques in short term tissue cultures. Aqueous extracts of hatching chick stomach mucosa selectively suppressed mitotic activity in younger chick stomach epithelia in vitro, but did not affect the proportion of cells entering mitosis in developing intestine, skin, or mesenchyme. The tissue specificity of this inhibitory effect was further supported by the fact that mitotic activity in stomach epithelial explants was not affected by an extract of tissue other than stomach mucosa, namely, hatching chick stomach muscle. Heating the mucosal extract to 60 C for 1 hr destroyed its inhibitory properties, suggesting that a protein was involved in this effect. No requirement for epinephrine and hydrocortisone for this mitotic suppression could be demonstrated in this study.