The cross-ply arrangement of collagen fibres in the submucosa of the mammalian small intestine.

Whole-mount preparations of the submucosa were made from the small intestine of rats, guinea-pigs, rabbits and sheep. In the distended intestine the collagen fibres ran straight and approximately parallel to the serosal surface. They formed a characteristic lattice, with two arrays of fibres running diagonally in a clockwise and an anticlockwise direction, and making an angle of 50 degrees-55 degrees with the longitudinal axis of the intestine. This collagen-fibre lattice was flexible and changed with the movements of the intestinal wall; when the radial distension predominated, the angle between collagen fibres of the submucosa and longitudinal axis of the intestine increased to 60 degrees-65 degrees, and when the longitudinal distension predominated the angle decreased to about 30 degrees.