243 



- 1 9 5 - 



J. Compar, Neurol. 93:241, I950 



In a series of experiments to determine the site of action of 

 bacterial pyrogens, spinal cords of cats and dogs were trans- 

 ected at various levels. One group was used for control purposes 

 The rest received PYROMEN intravenously or intraperitoneally in 

 cumulative dosages ranging from 300 to 11,000 gammas. In addi- 

 tion one control received I50 units of hydase for 10 doses; one 

 animal received 225 gammas of typhoid concentrate and 35 tng. 

 "Pyrexin", and a second was given 3*856 gammas of typhoid con- 

 centrate alone. One animal had received old and inactive 

 pyrogen. 



The animals were sacrificed at intervals ranging from 8 to 139 

 days after administration of PYROMEN. Cords of animals living 

 30 to 50 days after transection revealed new growth of neurons 

 across or into cut regions. There was some connective tissue 

 scarring at severed ends, but no glial barrier. Rather a 

 blending of spinal cord parenchyma with a loose tissue contain- 

 ing non-nervous tissue cells had occurred. Through such regions 

 nerve fibers had in some cases penetrated into or through the 

 scar along strands of reticulum-like cells. Serial sections 

 and staining by the pyridine-silver method revealed that they 

 were derived from severed or injured nerve roots, nerves to blood 

 vessels and intrinsic spinal cord neurons. No evidences of 

 functional regeneration were seen. 



690. WDTDLE, W. F. 



Spinal cord regeneration associated with a cellular reaction in- 

 duced by administration of a purified bacterial pyrogen 



International Anatomical Congress, July 24-28, 1950. Abst., 

 Proc. of the Congress, p. 196. 



Transected spinal cords of dogs and cats, when given varying 

 dosages of PYROMEN for periods of time ranging from 8 to 61 days, 

 revealed clear-cut evidence of neuron growth into or aoross the 

 cut ends. Some connective tissue scarring between severed ends 

 and the usual amount of retrograde degeneration were observed. 

 There was no glial barrier, but a blending of spinal cord paren- 

 chyma with connective tissue was noted; through such areas, 

 nerve fibers could be seen growing into the scar. The nerve 

 fibers were derived from severed or injured posterior and 

 anterior nerve roots, vascular and meningeal nerves, and intrin- 

 sic spinal cord neurons. Numerous blood vessels were observed 

 at scar-cord juncture and there were many macrophages at the 

 interstices between strands of non-nerve cells and the nerve 

 fibers. 



