osteoblast /os″tē·əblast′/ [Gk, osteon + blastos, germ] , a bone-forming cell that is derived from the embryonic mesenchyme and, during the early development of the skeleton, differentiates from a fibroblast to function in the formation of bone tissue. Osteoblasts synthesize the collagen and glycoproteins to form the osteoid matrix and, with growth, develop into osteocytes. See also ossification. −osteoblastic, adj.