LM showing the periosteum on the surface of a bone (decalcified) from an elderly person. The outer cortex, to the right, contains many closely packed osteons and Haversian canals (HC). The bony matrix is intensely eosinophilic because of the high collagen content. The periosteum (Pe) consists of an outer fibrous layer with densely packed collagen fibers. Its inner surface contains cells that vary in morphology depending on age and functional state. Here, bone growth is complete, and these cells are fibroblasts that seem inactive. Surrounding connective tissue, to the left, shows several neurovascular structures —arterioles (A), venules (V), and a small nerve fascicle (N). 130×. H&E.