186 Discussion 



glands in the velvet were innervated by both myelinated and un- 

 myelinated fibres. Nerve ends were also abundantly demonstrable in 

 the corium, epidermis and on hair follicles. The arteries received 

 medullated and unmedullated fibres with terminations localized in the 

 adventitial and medial coats. Previously, I had assumed that the arteries 

 of the velvet, because of their similarity in structure to umbilical arteries, 

 might be devoid of any innervation. 



We also denervated an antler in each of two white-tail deer (Wislocki 

 and Singer, 1946), in late spring, and followed the subsequent antler 

 development. The denervated antlers showed no changes attributable to 

 possible loss of trophic neural influences. The denervated antlers grew to 

 practically the same size as the antler on the opposite, normal side. Some 

 deformation present in the denervated antlers seemed to be due entirely 

 to repeated bruises and several fractures which they sustained because 

 of the loss of sensation in the velvet. 



Boyd: There were no superior cervical sympathectomies — chronic 

 ones? 



Wislocki: No, we did nothing of that sort. 



Huggett: You did not test them experimentally by stimulating to see 

 how the vascular plexuses proliferate ? 



Wislocki: No. We did not do that. 



Matthews: One or two points: first of all, if the initiating of the growth 

 of the antlers is due to a growth-stimulus substance, how is it that 

 if you have a deer that has been castrated as a fawn and has grown no 

 antlers at all, and then you give it a shot of testosterone, the antlers 

 start growing? And furthermore, there is the other case of the male deer 

 which never grow antlers at all. They are fairly common in Scotland and 

 are known as hummels. They are not castrates ; there is nothing wrong 

 with them except that they just do not grow any antlers. 



Wislocki: In regard to those questions, I can merely say that it is a 

 strange fact that a fawn, if castrated, grows no antlers at all. However, 

 if it is given later a daily single shot of testosterone propionate, this pro- 

 cedure will trigger a growth-promoting influence which initiates antler 

 growth. Why this is so, I do not know, but the pituitary growth- 

 promoting factor apparently remains dormant until it receives an initial 

 signal, either, normally, from the developing testis, or, in the castrated 

 deer, by administration of a single dose of testosterone propionate. 

 Without this signal, a castrated fawn will remain, forever, without any 

 antlers. With regard to so-called "hummels", that is, male deer sexually 

 active but bearing no antlers, I have no first-hand knowledge. Perhaps 

 the absence of antlers in these deer is a genetic deficit rather than a 

 hormonally- induced condition. It would be interesting to attempt to 

 stimulate antler growth in such animals by the administration of 

 hormones. 



Dempsey: Could it be the pituitary or could it be the end-organ that 

 is triggered? 



Wislocki: Well, there is always the possibility of the end-organ. W x e 

 have considered that but we have so little evidence that they ever got 

 the direct effect on the end-organ. 



