Murine fetal colon in vitro: assays for growth factors.

The growth of murine fetal colon was examined in two tissue-culture systems: an organ-culture assay and a modified Hamburger assay for the production of cell colonies in a semi-solid medium. The organ-culture system was found to support the normal development of the intact colon for several weeks, but epithelium separated from mesenchyme produced terminal squamous differentiation within 1 week. Gastrin analogues permitted continued growth of the epithelium, but produced a maturation arrest which was reversible by the removal of the hormone and after prolonged culture. Epidermal growth factor (EGF) produced some mesenchymal proliferation but, as with the other reagents tested, had no effect on the epithelium in organ culture. Analogues of gastrin produced enhanced colony formation in cells from fetal colon and neonatal colon obtained up to 2 weeks post-partum, but had no effect on adult colon. No enhanced colony formation was seen with EGF, oestrogen, dexamethasone, indomethacin, progesterone, prolactin and testosterone. Mouse fetal colon in organ culture can be a useful model for screening possible trophic factors for the colon in a qualitative way, while the colony-assay system can be used to provide quantitative results.