Crypt regeneration in adult human colonic mucosa during prolonged organ culture.

Using a system designed to preserve, in vitro, both the epithelial and the connective tissue elements, we have maintained adult colonic mucosa in organ culture for up to 336 hours and have investigated the sequential morphological changes which occur. During the first 48 hours, normal micro-architecture is preserved, but there is progressive loss of cytoplasmic mucin from crypt cells. Subsequently, accelerated degenerative changes develop; cells are lost from the crypts and, because cell proliferation in the crypt is reduced, these lost cells are not replaced. For a time, the crypts are represented by discrete acinar formations or clusters of cells in the lamina propria, apparently discontinuous with the intact surface epithelial layer. These remnants manifest intense proliferative activity during the period between 72 and 96 hours after explantation, leading to the restoration of well formed crypts lined by columnar epithelial cells between 120 and 144 hours; differentiation of goblet cells ensues and this state of virtually normal structure persists until the termination of culture between 186 and 336 hours. It is concluded that the determination of normal crypt structure and of crypt-cell differentiation is governed by intrinsic control mechanisms although these may be subject to extrinsic modulation. Whether or not the degeneration phase can be eliminated, it is clear that long term culture of adult human colonic mucosa is possible. Such a system may be useful in the study of mucosal function and of mucosal response to drugs, carcinogens and trophic factors.