Fig. 1. Osteocyte processes are associated with collagen cleavage. Cortical bone sections stained with Bodian silver stain (A,B), Giemsa (C,D), and collagen-cleavage-specific antibody (E-I). (A) Osteocytes are surrounded by many well-defined cell processes emanating from the lacunae and extending into the pericellular bone matrix to generate a mesh-like appearance in this 30-day-old wild-type mouse. (B) At 40 days of age, the network is even more highly developed. The progressive development of osteocyte processes can be appreciated more easily in sections from wild-type mice stained with Giemsa (C,D). (C) Bone section from a 20-day-old wild-type mouse demonstrating weakly outlined osteocyte processes (arrows). (D) In bone from a 40-day-old wild-type mouse, processes now appear more defined as canal-like structures radiating from the osteocyte lacuna (arrows). (E) Collagen cleavage is modest in the cortex of 30-day-old wild-type mouse and more obvious at the periosteal surface (p and arrow). The endosteal surface (e) in this section displays no staining. (F) Conspicuous staining of the osteocyte processes in a 40-day-old wild-type mouse. Clearly outlined processes are radiating from the osteocytes. (H) High-power magnification of osteocytes and their associated processes radiating from lacunae (H). (I) Punctate staining demonstrates areas cross-sectioned osteocyte processes. (G) Negative control stained with peptide-absorbed antiserum. Bars, 10 µm (A-D,H,I), 30 µm (E-G).