The Growth Cycle of Deer Antlers 177 



strongly basophilic when stained with methylene blue and in- 

 tensely metachromatic with toluidine blue, and gives an intense 

 reaction for alkaline phosphatase. The basophilia and meta- 

 chromasia of the lacunar capsules bespeak the presence of a 

 sulphated acid mucopolysaccharide and a resemblance to 

 cartilage. However, on other grounds, including the presence 

 of a dense meshwork of collagen, the arrangement of the cells 

 and the pattern of the blood supply, the preosseous tissue 

 differs markedly from ordinary hyaline cartilage and endo- 

 chondral bone formation as seen in the growing epiphyseal 

 regions of long bones. Unlike endochondral bone formation 

 where the cartilage cells perish, the preosseous corpuscles of the 

 antlers appear to become directly converted into osteocytes. 



Throughout their entire period of growth, the antlers are 

 supplied with blood by the arteries of the velvet (Waldo, 

 Wislocki and Fawcett, 1949). Venous drainage occurs at 

 first internally through the pedicle (April, May), but by July 

 this pathway has been completely supplanted by a series of 

 efferent veins which are located in the velvet. Recurrent 

 arterioles at the growing tips of the antlers connect the 

 arteries of the velvet with the capillaries and venous channels 

 of the antler shaft. A ligature tied around the antler base in 

 mid-June produced no permanent interference with either 

 the blood supply or growth, whereas ligation in July caused 

 cessation of growth and death of the antler. These results 

 indicate that in June there are enough internal vascular 

 channels to by-pass the blood around the site of the ligature, 

 whereas in July such internal channels are no longer available. 

 Natural shedding of the velvet appears to be associated with 

 ossification of the peripheral zone of the antler shaft, a process 

 which restricts the venous return from the interior of the 

 antler and obstructs the circulation. 



With respect to the mode of growth of antlers, in recent 

 interesting experiments two fallow deer were injected with 

 radioactive phosphorus (Bernhard, Brubacher, Hediger and 

 Bruhin, 1953). In a stag with growing antlers, a radiogram 

 showed a gradient of phosphorus deposition which was 



