THE ULCERATION-ASSOCIATED CELL LINEAGE (UACL) REITERATES THE BRUNNERSGLAND DIFFERENTIATION PROGRAM BUT ACQUIRES THE PROLIFERATIVE ORGANIZATION OF THE GASTRIC GLAND

The ulceration-associated cell lineage (UACL) develops in the human ga strointestinal mucosa after ulceration; it grows out from the bases of adjacent crypts and ramifies in the lamina propria to form a new glan d, finally giving rise to a duct by which the glandular secretion and indeed cells are carried to the surface. Using immunocytochemistry and in situ hybridization with S-35-labelled riboprobes, we have defined the pattern of trefoil peptide gene expression (pS2; human spasmolytic polypeptide, hSP), epidermal growth factor/urogastrone (EGF/URO), and the distribution of cell proliferation during the development of the UACL, as indicated by immunostaining for proliferating cell nuclear an tigen (PCNA). Our studies reveal that the morphogenesis of the UACL sh ows a marked morphological resemblance to developing Brunner's glands; the pattern of trefoil peptide gene expression during UACL developmen t is also very similar. However, trefoil peptide gene expression in th e mature UACL complex is unique amongst gastrointestinal cells. The ma ture UACL shows a distinctive proliferative organization: while the ea rly buds and glands are non-proliferative, apparently being fed by cel ls from the parent crypts, a definitive proliferative zone develops wi thin the duct. This, of course, corresponds to the location of the gas tric gland proliferative zone. We propose that while the UACL shows no vel features, it shares its differentiation programme with Brunner's g lands, but its pattern of cell renewal eventually is that of the gastr ic gland.