Light micrograph of collagen fibres in a breast. The fibres are pink and have a wavy or haphazard arrangement. The nuclei of fibroblasts, the cells producing the fibres, are the scattered small blue ovoid structures. The collagen fibres are part of the connective tissue which helps hold together various human organs. Haematoxylin and eosin stained tissue section. Magnification: 200x when printed at 10cm.