Membranous bone formation, non-decalcified section, micro
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Non-decalcified section of the surface of an endosteal bone spicule, micro. Active osteoblasts, with abundant cytoplasm and hypertrophied Golgi zones, seen as ovoid paranuclear clear zones, are actively secreting a carpet of non-mineralized bone matrix called osteoid. The latter stains intensely red while the mineralized bone matrix deep to the osteoid stains blue-green.