Pedicle and first antler formation in deer: Anatomical, histological, and developmental aspects

Szuwart

2007

Journal of Morphology

The periodic replacement of antlers is an exceptional regenerative process in mammals, which in general are unable to regenerate complete body appendages. Antler regeneration has traditionally been viewed as an epimorphic process closely resembling limb regeneration in urodele amphibians, and the terminology of the latter process has also been applied to antler regeneration. More recent studies, however, showed that, unlike urodele limb regeneration, antler regeneration does not involve cell dedifferentiation and the formation of a blastema from these dedifferentiated cells. Rather, these studies suggest that antler regeneration is a stem-cell-based process that depends on the periodic activation of, presumably neural-crest-derived, periosteal stem cells of the distal pedicle. The evidence for this hypothesis is reviewed and as a result, a new concept of antler regeneration as a process of stem-cell-based epimorphic regeneration is proposed that does not involve cell dedifferentiation or transdifferentiation. Antler regeneration illustrates that extensive appendage regeneration in a postnatal mammal can be achieved by a developmental process that differs in several fundamental aspects from limb regeneration in urodeles.

Section: Basic Aspects Of Antler Regeneration and Comparison With Limmentioning

confidence: 99%

Deer antler regeneration: Cells, concepts, and controversies

Szuwart

2007

Journal of Morphology

“…Pedicles develop during puberty due to androgenic stimulation of specialized areas of the frontal periosteum, referred to as the antlerogenic periosteum (Hartwig and Schrudde 1974;Goss 1983;Goss and Powel 1985;U. Kierdorf and Kierdorf 2002).…”

Section: Introductionmentioning

confidence: 99%

Pedicle and antler fusion and double-head formation in a sika stag (Cervus nippon)

Lutz²,

2004

Eur J Wildl Res

A case of pedicle and antler abnormality in a 12-14 year old sika stag shot in January 2003 in Schleswig-Holstein (Germany) is presented. The abnormality combines fusion of pedicles and antler bases with subsequent double-head formation. Double-heads result from growth of new antler bone without casting of the previous hard antlers. In consequence, two consecutively formed antlers are present in an individual. The stag's skull showed a plate-like osseous structure whose broad and slightly elevated central portion was identified as the fused pedicles. The peripheral parts of this osseous plate constituted the second antler growth of the (former) double-head. A cast pair of antlers, which were fused at their bases, had been found in a neighbouring hunting district in the summer of 2002. The close fit between the casting surface of the fused antlers and the surface of the pedicle/antler structure on the stag's skull indicated that the antlers had been grown by this stag and were belatedly cast from his fused pedicles. The fused antlers thus constituted the first antler growth of the doublehead. We suppose that the broad connection between the fused antlers and the fused pedicles prevented antler casting at the normal time and thereby caused the double-head condition. The presentation of this antler abnormality is taken as an occasion to discuss the significance of pedicles for the normal casting and regeneration of antlers.

“…In summarizing our current knowledge, it has been suggested that antler regeneration can be characterized as a stem cell-based dedifferentiation-independent epimorphic process that depends on the periodic activation of stem cells located in the PP [15,16] . To allow periodic antler regeneration throughout the life of a deer, the stem cell pool in the PP must be maintained by lifelong selfrenewal.…”

Section: Histo-and Morphogenesis Of the Regenerating Antlermentioning

confidence: 99%

“…Furthermore, it was shown that in vitro cells from the PP can be induced to differentiate along different mesenchymal (osteogenic, chondrogenic, adipogenic) lineages, thereby indicating their multipotency [15,64] . Cells from the AP, which are assumed to give rise to those of the PP [13,16] , were recently reported to differentiate into muscle precursor cells and cells resembling neurons upon cultivation in appropriate media [15] . That AP cells are probably able to differentiate into nerve cells is not surprising given the presumed derivation of the AP from the neural crest.…”

Section: Histo-and Morphogenesis Of the Regenerating Antlermentioning

confidence: 99%

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

2010

Gerontology

Background: Compared with other vertebrate taxa, mammals possess a very limited capacity for appendage regeneration. The antlers of deer are an exception in that they are periodically lost and fully regenerated throughout the life of an individual. Objective: In this paper we compare certain aspects of antler regeneration with regenerative processes in other vertebrates. Methods: Review of the literature. Results: Recent studies suggest that antler regeneration is a stem cell-based process and that these stem cells are located in the pedicle periosteum. There is evidence that signaling pathways known to operate during appendage regeneration in other vertebrates are also activated during antler regeneration. There are, however, also differences between antlers and other systems of epimorphic regeneration. Thus, contrary to amphibian limb regeneration, signaling from the wound epidermis appears not to be of crucial importance for antler regeneration. Healing of the casting wound typically involves no or only minor scarring, making antlers interesting subjects for researchers attempting to reduce scar formation during wound healing in humans. The fact that despite their enormous growth rate the antlers of intact and castrated deer appear to be resistant to malignant transformation furthermore offers research opportunities for cancer biology. Conclusions: Studying antler renewal as an example of mammalian appendage regeneration may provide crucial information for regenerative medicine to achieve its ultimate goal of stimulating limb regeneration in humans. A deeper understanding of the developmental mechanisms involved in antler renewal can also be useful for controlling induced regeneration processes in mammals.