Everything above this is epidermal. The hair grows out through the tube of epidermis. Also, epidermal cells form the oil gland that supplies the hair and the mesodermal cells around the hair form the smooth muscle that attaches to the hair. There are a number of hard mineralized tissues in vertebrates. Bone is the most common, but we also see cartilage, dentin, and enamel.
Bone is formed by osteoblasts .
The matrix is hydroxyapatite. The osteoblasts sit in little lacunae which are interconnected by canaliculi . The hard bone which makes up the outer part of bones is compact bone . The osteoblasts sit in circles around a Haversian canal . It contains blood and lymph vessels and a nerve fiber.