DNA synthesis in human duodenal biopsies maintained in organ culture

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Abstract
Incorporation of3H-thymidine during organ culture was studied in duodenal biopsies from 14 patients. Pulse-label at various intervals disclosed active incorporation during the first 2 h in culture. Labelling index declined to low levels at 3–4 h. Thereafter incorporation increased again and persisted throughout the rest of the culture period of 11 h. The DNA synthesis rate of crypt cells between 4 and 11 h in culture was calculated in 5 patients after pulse-label and continuous labelling of expiants in parallel culture. The rate of entry into DNA synthesis was about 24 cells per 1,000 crypt cells per hour in flat, coeliac biopsies, versus 9–13 in controls. Gluten did not influence DNA synthesis rate, whereas wheat germ lectin inhibited DNA synthesis. Counting of the total number of mitoses and labelled fraction of mitoses disclosed active crypt cell renewal in flat, coeliac biopsies. In normal-appearing biopsies no mitoses were labelled, indicating delayed exit from S-phase or long duration of G2-phase in these explants.