Fig. 2

Histological presentation of the involved tissue types. An overview of the region is depicted in the lower center (black frame). The newly formed bone tissue inside of the drill hole is stained darker purple than the surrounding old bone tissue. Histological details in higher magnification are arranged around the overview: a The border of the drill hole, with old bone tissue on the left and darker newly formed bone tissue on the right is still visible. b Inside of the newly formed bone a large number of secondary osteons in all stages of formation are present. They are surrounded by the remnants of primary plexiform bone. c Parts of the drill hole are filled with fibrous soft tissue that penetrated the defect from the periosteal side. d The cortical bone of the medial bulge consists of plexiform bone. e Plexiform bone is also found inside of the defect. It consists of a network of woven bone (asterisks) on which parallel fibered bone (arrow heads) was laid down. This primary type of bone tissue is continuously replaced by the lamellar bone of secondary osteons. Micrographs of undecalcified thin ground sections stained with Levai-Laczko dye