Slide 24 - Compact Bone - dried ground, cross-section of shaft of mature long bone.  This is an unstained thin slice of dried bone, in which the bony matrix appears as pale yellow and the spaces once filled with cells or blood vessels appear black.  (Look for a fairly thick area with spidery black lines in it.)  The chief characteristic of such compact bone is the presence of many longitudinal Haversian systems (osteons), consisting of concentric lamellae or layers of bony matrix laid down around a blood vessel.  You see these ringed tubes cut transversely and, if you reduce the light sufficiently, you will see that the collagenous fibers contained in the matrix are running in different directions with successive layers (or lamellae) of each Haversian system, thus providing even greater strength to the tissue.  Confined in the lamellae, which they themselves deposited, are the osteocytes within their lacunae.  The cells have been dried out here but the lacunae and the thin, spidery interconnecting canaliculi remain.    What is the significance of the canaliculi?  How are nutrients passed from osteocyte to osteocyte within the bony matrix?

Notice that bone is highly vascular.  What does this tell you about the level of metabolic activity in bone?  How does this differ from the situation in cartilage?