1.   The factors that influence the size of the proliferative compartment are less clear, though in rats there are genetic differences.

2.   This is reflected in a retained capacity for DNA synthesis which leads to an expansion or a shift of the proliferative compartment towards the upper portions of the crypt.

3.   A trained observer selected longitudinal crypts and counted labelled and unlabelled cells in the proliferative compartment, entering data directly into a BBC Microcomputer.

4.   Previous studies have shown that expansion of the proliferative compartment toward the surface of the colonic gland is a common feature in subjects at high risk for colorectal cancer.

5.   In the former the oesophagus increases the growth fraction by hyperplasia and elongation of the proliferative compartment.

6.   Lipkin proposed that upward expansion of the proliferative compartment of the crypts of the large intestine occurs before adenoma development.

7.   We did not, however, detect any upward expansion of the proliferative compartment in the background crypts.

8.   In the first stage, crypt cells that can synthesise DNA spread beyond the normal proliferative compartment into the upper part of the gland.