abnormal osteoblast cell number decreased osteoblast cell number MP:0000058 MP:0004989 MPheno.ontology decreased osteoblast formation reduced osteoblast cell number reduced osteoblast formation reduction in the number of skeletogenic cells that secrete osteoid, are capable of producing mineralized (hydroxyapatite) matrix, are located adjacent to or within osteoid tissue, and arise from the transformation of a preosteoblast cell