Histological studies of bone formation during pedicle restoration and early antler regeneration in roe deer and fallow deer

Abstract

The purpose of the present study was to examine the process of bone formation in the regenerating cranial appendages of roe deer (Capreolus capreolus) and fallow deer (Dama dama) during the early postcasting period. After the antlers are cast, osteoclastic and osteoblastic activities lead to a smoothing of the pedicle's separation surface, a strengthening of the pedicle bone, and a partial restoration of the distal pedicle portion that was lost along with the cast antler. Initially, bone formation occurs by intramembranous ossification, but early during the regeneration process cartilage is formed at the tips of the cranial appendages, and is subsequently replaced by bone in a process of endochodral ossification. Shortly after the antlers are cast, the cambium layer of the periosteum in the distal pedicle is markedly enlarged, which suggests that the periosteum serves as a cell source for the bone-forming tissue covering the exposed pedicle bone. The histological findings of our study are consistent with the view that the bony component of the regenerating cranial appendages of deer is largely derived from the pedicle periosteum. Based on findings in other bone systems, we speculate that stem cells that can undergo both osteogenic and chondrogenic differentiation are present in the pedicle periosteum. The early onset of chondrogenesis in the regeneration process is regarded as an adaptation to the necessity of producing a huge volume of bone within a short period. This parallels the situation in other cases of chondrogenesis in membrane bones. Anat Rec Part A 273A: 741-751, 2003.

Deer Antlers – A Model of Mammalian Appendage Regeneration: An Extensive Review

“…However, it was later shown that antler regeneration can occur when the skin is not involved, leading to the formation of (stunted) 'skinless antlers' [55] . In contrast, our group suggested that the regenerating antler is formed by cells originating from the pedicle periosteum (PP) [40,41,43] . This view was initially based on the morphological analysis of double-head antlers, demonstrating that when the old antler is not cast, the regenerated antler develops as a periosteal exostosis from the distal pedicle [56] .…”

“…During typical skin wound healing in adult mammals, the initially formed granulation tissue is transformed into the scar tissue [46,48] . A capillary-rich fibrocellular tissue resembling granulation tissue has also been reported to occur between the pedicle bone and the scab during casting wound healing [39,41,42] . The fate of this tissue has not been studied so far, but it is assumed that if a scar is formed during antler regeneration it is derived from it.…”

“…Starting from this skin rim, epidermal cells move over the wound area, leading to its epithelialization ( fig. 4 b) [41] . The migrating epidermis dissects through the wound area by moving underneath the scab [34,41] , as has also been observed in other cases of mammalian skin wound healing [48] .…”

“…4 b) [41] . The migrating epidermis dissects through the wound area by moving underneath the scab [34,41] , as has also been observed in other cases of mammalian skin wound healing [48] . Electron microscopy and immunohistochemistry demonstrated early formation of a basal lamina during antler regeneration.…”

“…Antler casting is followed by some bone restoration in the pedicle that partly compensates the bone loss occurring at antler casting [33,34,41,42] . As this compensation is, however, only a partial one, the pedicles decrease in height with age.…”