part of develops from ends during starts during bone tissue death connective tissue perichondrium periosteum eriksegerdell A membrane that lines the outer surface of all bones, except at the joints of long bones. It consists of dense irregular connective tissue, and is divided into an outer fibrous layer and inner osteogenic layer. The fibrous layer contains fibroblasts, while the osteogenic layer contains progenitor cells that develop into osteoblasts, which are essential to the healing process. XAO:0004503 2013-04-10T19:57:52Z xenopus_anatomy NF stage 45