THE GROWTH CYCLE OF DEER ANTLERS 



George B. Wislocki 



Department of Anatomy, Harvard Medical School, Boston, Massachusetts 



The antlers of deer are deciduous, being annually renewed. 

 In the Virginia deer (Odocoileus virginianus) in its natural 

 habitat, they begin to grow visibly in April or May, reach 

 maturity in August and the velvet is shed in September. The 

 mature antlers, consisting of bare, dead bone, remain in place, 

 firmly attached until mid-winter when they are shed. 



Antlers grow by the addition of new material at the ex- 

 tremity of the beam and at the tips of the tines as they arise. 

 The growing tip moves away from the antler pedicle, deposit- 

 ing a column of bone which, once laid down, does not increase 

 appreciably in diameter as it matures. All stages of growth 

 and maturation can be seen in a single growing antler; the 

 bone nearest the antler base is the oldest and most mature, 

 whereas that at the tips is most recent and in process of 

 formation. 



Microscopically, the mode of bone differentiation at the tips 

 of the growing antlers is observed to be intermediate, in a 

 number of important respects, between intramembranous and 

 endochondral ossification (Wislocki, Weatherford and Singer, 

 1947). In the growing tips beneath the velvet, germinal, 

 preosseous and osseous zones are visible. The germinal zone 

 located immediately beneath the velvet consists of large fusi- 

 form and stellate cells with extremely basophilic cytoplasm and 

 showing numerous mitoses. The cells of the preosseous zone 

 lie in lacunae contained within a matrix. The matrix consists 

 of a dense meshwork of reticular, collagenous fibres and of a 

 ground substance; the latter is metachromatic following 

 staining with toluidine blue and gives an alkaline phosphatase 

 reaction. Each lacuna is enclosed by a capsule which is 



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