early names in glial history
Dear Jessa Netting, Here his first name and a few lines from H.Hydén (ed.), The Neuron, p. 40ff. which descriebe his famous book. Deiters, Otto Friedrich Carl: Untersuchungen über Gehirn und Rückenmark des Menschen und der Säugetiere. Hrsg. u. bevorwortet v. Max Schultze nach dem Tode des Verf. - Braunschweig, 1865, 8°, XVII S., (1 Bl.), 318 S., 1 Anz.S., mit 6 gefalt. lith. Taf. in Imperial-Oktav gezeichnet von O.F.C. Deiters, HLdrBd. d.Zt.; St. verso. Tit. Garrison/Morton No.1271. "Deiters (1834-1863) holds the position of "Privatdozent der Medizin" when he dies at 29 years of age. His «Studies on brain and spinal cord of man and mammals» are found in his personal estate. They are in the form of an unfinished manuscript.. Deiters' outstanding text begins with the following words: «I have put myself to the task of making the central organs of the nervous system the subject of a thorough analysis in a comprehensive series of investigations...» Deiters' histologic methods include cutting of thin sections and isolation of individual cells as well as a large battery of chemical pre- and post-treatments. His beautiful drawings betray, in addition to artistic talent, remarkable mastery of these methods; his technique of isolating (micro-dissecting) individual nerve cells requires an enviable micromanipulatory control of hands, armed only with the teasing tools - needles and the like - of that day. Among the many non-man mammals which Deiters studies, oxen seem to be his favourite subjects. There are not many areas of the central nervous system he does not draw into his investigation. What was the image of truth which emerged? First of all: what, for Deiters, was a nerve cell (Ganglienzelle)? «I don't know if there is an absolute defintion; however, I call every cell which is continuous with fragments of unequivocal nerve fibers, a nerve cell.» He approaches this problem of neuron definition by describing all recognizable (morphologic) properties of those cells which may be assumed to be nerve cells. These properties may then be applied to other cells as criteria of their neuronal identity. Deiters' «schematic picture» (schematisches Bild) which resulted from this analysis could, in his opinion, be applied to practically all known CNS nerve cells. That part of his picture which is most pertinent to this review can be summarized as follows: the nerve cell is a cell which bears on its soma one axon and several dendrites. This characterization of the nerve cell leaves room for an interesting elaboration. This elaboration was very much part of Deiters' picture. The reason that I treat it separately is that, in retrospect, it constitutes a side-branch of the neuron's ideogenetic tree: it was cut off by students of the nerve cell who came after Deiters. The elaboration is that nerve cells bear a second system of axons which emanate from the dendrites; (the first system consists of the one axon which issues from the soma). A summary of the nerve cell compartments as proposed by Deiters shall now be given. The nerve cell body (Körper der Zelle) contains a nucleus with a nucleolus. The remainder of the soma is «an irregularly shaped mass of protoplasma of granular appearance». From the fairly smooth contour of the soma there arise, in a gradual transition, a variable number of dendrites. Because of the great similarity between dendrites and soma (Deiters emphasizes this point) he names them «protoplasmic processes» (Protoplasmafortsätze). The dendrites repeatedly bifurcate; they finally become so thin that they «lose themselves in the porous ground-substance»; they cannot be seen to connect nerve cells with one another. It is impossible to confuse dendrites with axons. Deiters distinguishes two parts of the axon: the «axonal process» (Nervenfaser- oder Axencylinder-fortsatz) i.e., the portion of the axon seen to be directly attached to the soma; and the «axon proper» (Axencylinder), the more distal, myelinated portion of the axon. The axonal process - always one of its kind to a cell body - is clearly distinct from the protoplasmic processes: among other things, it is far less granular than the dendrites and it is stiffer; it is fairly straight, always unbranched and has a smooth contour. The point of emanation of the axonal process is usually on the cell body; it may also be on a proximal, stout dendrite branch. The axonal process narrows; .. The smallest diameter is reached «at a distance which approximately equals the diameter of the cell body». Then the axon becomes wider and assumes its myelin sheath. It is obvious that Deiters, with great clarity, gives the first description of those structures which we now call the initial segment of the axon and the axon neck. (I propose that the somewhat macabre designation «axon neck» - macabre indeed: where is the head? - be replaced by «Deiters' constriction».) One of the similarities between dendrites and somata which Deiters notices may, at first, seem somewhat surprising to us: it is that both of them bear axons. This observation brings us to Deiters' fourth and last nerve cell compartment, the «second extensive system of very small axons which are attached to the dendrites». These small axons differ from the large axon which sprouts from the soma, in triangular bases. Only rarely, as Deiters admits, does one see them surrounded with a myelin sheath. Although not explicit, it may be inferred that Deiters conceived these small axons to be only fragments which have one end attached to the dendrite and the other end broken off... Deiters did not depict their (i.e. the second order axons) mode of branching he did depict two such axons which acquire a myelin sheath. I am convinced that Deiters in describing his second system axons has given us an accurate portrayal of boutons terminaux and their pre-terminals. His morphologic interpretation diverges from ours: these small axons form, for him, «a second system of egressing axons» (ein zweites System abgehender Axencylinder) (my spacing). His functional interpretation converges with ours: these small axons may very well have the office of interconnecting the nerve cells... In ending it should be said that we owe to Deiters' unique work a concept of the nerve cell which - one century old - comes very close to our own. All nerve cell studies of any significance performed since, have been influenced by the image of truth he left. Within the subsequent twenty-five years Deiters' image was to undergo some modifications and the nerve cell in which we now believe then emerged." H.Hydén (ed.), The Neuron, p. 40ff. With regards, Fritz-Dieter Söhn Antiquariat für Medizin MedRareBook