The spatial organization of the hierarchical proliferative cells of the crypts of the small intestine into clusters of 'synchronized' cells.

A statistical analysis of the distribution of [3H]TdR-labelled cells in longitudinal and transverse sections of crypts from the ileum of the mouse, indicated that there was a strong tendency for labelled or unlabelled cells to be associated in short vertical runs and lateral clumps, suggesting the presence of clusters of labelled cells on the sides of the crypts. A model is discussed for the cellular spatial organization of the crypt that proposes a vertical alignment of the cells within branches of the proliferative cell lineage. The model would predict vertical alignment of partially synchronized cells as well as some lateral clumping. In the present studies mitoses were not observed at higher levels in the crypt than labelled (S phase) cells. This observation would be predicted by the non-random spatial organization suggested by the model. The model would also make certain predictions concerning cell migration. These are discussed in relation to cell migration studies which include evidence that migration continues in the absence of mitotic activity.