Central nerve terminals in the mamalian spinal cord and their examination by experimental degeneration

Since the discovery by Held (1897, 1902) of the boutons terminaux in the central nervous system, and the confirmation of this discovery by Aurebach (1899) and Cajal (1908), the function of these structures as synapses has gradually come to be recognised. The present study is an attempt to reinvestigate these boutons and their relations to nerve cells in the cat; and also to observe the changes they undergo following section of the nerve fibres of which they are the terminals. II. Technique. The silver methods of staining the nervous system have been often criticised in that they did not give consistent results. It is believed that this is due, partly at least, to imperfect fixation. Nervous terminals of the grey matter are highly susceptible to post-mortem destruction, and with the ordinary method of placing small pieces of tissue into a quantity of fixative, it is quite likely that changes occur in the finest fibres and their terminals before they are fixed. Further, it has been found that the presence of blood in the capillaries of the grey matter tends to make the tissue refractory to the silver stain. In these studies, therefore, the method of injecting the fixative into the living animal has been used, with the result that in successful impregnations all of the intra-central nerve terminals have been stained.