Studies On The Role Of Antlerogenic And Pedicle Periosteum In Development Of Antler In Sika Deer (Cervids Nippon)

Deer antlers are not only precious traditional Chinese medicine, but also a novel biomedical model as they can fully regenerate once lost, a phenomenon that is not paralleled by other mammalian organs. However, research on antler development and regeneration has not attracted as much attention as it deserves.Many results so far achieved are controversial, which is known as"bones of contention". For example, for the mechanism underlying antler development and regeneration, some scholars thought that it is controlled by a centre that is located in the central nerve system; while others considered that it is the pedicle skin growth that gives rise to regenerating antlers; and the rest group reported that antler formation is a stem cell-based process and antler stem cells reside in the antlerogenic periosteum.It is still debating what tissue is the key for antler development. It is not known what controls antler shape. Insulin-like growth factor 1 is the key molecule that stimulates antler growth, which is achieved through binding to its receptor (IGF1R).However, whether antlerogenic periosteum contains IGF1R is not known.Through my PhD research, some of the mechanism of antler development has been revealed.These results have laid foundation for the increase in production of velvet antler and for the creation of mammalian wound healing and organ regeneration model.Sika deer were used in the study. My PhD project consisted of 4 experiments. Experiment I: Determine the key tissue type for pedicle and antler development through total antlerogenic periosteum deletion and transplantation; Experiment II: Determine the regional (anterior, posterior, lateral and medial) potential of antlerogenic periosteum for antler size and shape; Experiment III: Determine the tissue origin for antler velvet skin through insertion of a piece of impermeable membrane between pedicle bone and the enveloping skin; and Experiment IV: determine whether IGF1R distributes evenly or concentrates regionally in antlerogenic periosteum using Northern blot analysis, in order to substantiate the morphological findings.Experiment I: Pedicles and antlers did not grow from the periosteum-deleted future antler growth regions. In contrast, pedicles and antlers formed from the ectopic periosteum-grafted sites. These antlers also fell off from the pedicles and two-branched or three-branched antlers regenerated subsequently.Experiment II: Pedicles and antlers formed from the half-periosteum-deleted future antler growth regions. These antlers casted and regenerated normally, but their shape was abnormal. Brow tine was missing after loss of anterior antlerogenic periosteum, and deletion of the posterior only had negligible effects; Deletion of the medial part of periosteum seriously affect brow tine and bez tine, whereas loss of the lateral part almost no effects; All the grafted half-size periosteum formed pedicles and antlers, although all these antlers are deformed.Experiment III: Pedicles with the insertion of impermeable membranes still regenerated antlers, but these antlers were abnormal in that they did not have enveloping skin, instead covered by a layer of scab. Some of these skin-less antlers had rudimentary branches.Experiment IV: Based on the Northern blot analysis results, antlerogenic periosteum contains IGF1R, and IGF1R distribution was not even in the periosteum: anterior was higher than posterior; and medial was higher than lateral.Based on the results from my 4 experiments, I made following conclusions. Antlerogenic periosteum is the key tissue type that gives rise to pedicles and antlers; and this tissue type determines antler size and shape. The centre of antlerogenic periosteum is the centre for pedicle and antler growth. Pedicle and related tissue types plays assisting role in antler development. There exists regional difference in potential of antlerogenic periosteum for antler formation: anterior controls brow tine formation, medial controls brow tine and bez tine formation. Antlerogenic periosteum can only give rise to antler cartilage and bone tissue but not skin. Antler velvet skin originates from deer scalp skin. Antler regeneration is made possible by the existence of pedicle antler periosteum, and all these periostea are developed from antlerogenic periosteum. Antlerogenic periosteum possesses IGF1R, which supports the conclusion that IGF1 plays a significant role in antler development.