II. Vegetatives Nervensystem

A. Entwieklung und Histologie

Vorsitzender: Prof. Dr. 1. Pick (New York)

From the Central Stzte Institute for Nervous and Mental Diseases, Budapest

Phylogenetie Evolution of the Vegetative Nervous System

By

J. Bothr

With 5 Figures

Numerous experiments have been performed to determine the phylo- genesis of the vegetative nervous system, but no significant results have been obtained. This may be because researchers have not been able to diseover a correct approach to those questions which are of fundamental importance in the investigation of the phylogenesis of the vegetative nervous system.

The questions are: which multi-celled animals are they, whose evolution of the vegetative nervous system predetermines human conditions? What general determination of the vegetative nervous system is valid for all ani- mals? What is the fundamental basic element of the vegetative nervous system upon which such a determination can be bu i l t ? . . , etc.

Concerning these questions, the author's views are as follows: The evo- lution of man follows a direction separate from even that of multi-celled animals with a primitive nervous system. The ancestors of present-day Coelenterata, Echinodermata, Protochordata, Chordata and Vertebrata indicate the individual stages along this direction of development (Fig. 1). All these animals have numerous morphological characteristics in common; one fundamental characteristic is the permanent intra-epithelial position of the nervous system of the organism. The gradual development of the intra-epithelial nervous system of the organism, such as can be traced, gives a definite indication concerning the study of the evolution of the vegetative nervous system on ,correctly selected animals. All those nerve structures can be considered as belonging to the vegetative nervous system, that participate in the innervation of the apparatuses and systems (digestive, sexual, excretory and respiratory apparatus, internal secretory glands, circu- latory and heat-regulatory systems) of the vegetative life function of the organism (nourishment, growth, reproduction etc.). The fundamentally important basic element of the vegetative nervous system is the nerve cell which is, genetically, primary - - whereas the cell processes, the nerve

J. Bot~r: Phylogenetic Evolution of the Vegetative Nervous System 343

fibres and their endings are secondary. The vegetative nervous system is the entirety of all those nerve cells, irrespective of position, morphology, origin and nature, whose processes and nerve fibres constitute the inner- vation of the vegetative apparatuses and systems of the organism.

Group 8 Vertebrata

Group 2 Chordata

Group 1

Protochordata

(Hominidae) �9 Primates

C y d ; ~ t ; m ~ t ~ " " � 9

Cephalochordata Tunieata

Enteropneusta Pterobranchia Phoronidea Pogonophora �9

Griuoidea

Eehinodermata Ophiuroidea �9 Asteroidea Echinoidea �9 Holothurioidea �9

Anthozoa �9 Coelenterata Scyphozoa �9

Hydrozoa

(Hymenopt~ra) ( Hexapoda

. . . . . . . .

O ~ O Cephalopoda

O O Ot . . . . . . . .

(3 . . . . . . . . 0

0 I . . . . . . . . O O . . . . . . . .

o . . . . . . . . ;~ 0 . . . . . . . .

) 0 0 . . . . . . . .

0

0

TurbeIlarla

Ctenopho~a

Pori[era

|

Fig. 1. Scheme of the evolution c~ man; Linea vertebralis and Linea invertebralis.

w In the view of the author, three main constituent parts can be dis-

tinguished in the vegetative nervous system: the enteric nerve-ceU system in the wall of the digestive apparatus, the vascular nerve-cell system along the main vascular trunk, and the visceral part of the nervous system of the organism which innervates the vegetative apparatuses and systems.

344 J. B o~r:

These three main constituents of the vegetative nervous system differ fundamentally from one another, not only in their phylogenetic development but also in their ontogenetical, morphological and physiological properties.

a) The enteric nerve-cell system is the oldest part of the vegetative nervous system. It first developed in the wall of the digestive apparatus of the Coelenterata, and is today present in all animals. In appearance, the enteric nerve-cell system is very similar to the nervous system of the organism; it is almost an entodermal continuation of the ectodermal

Fig. 2. Scheme of the vegetative nervous system by Coelenterata. 1 : epidermis~ 2 : coelexa- teron, 8 ~-~ intraepidermal nerve-cell strand of the nervous system of the organism, 4 ~- diffuse

nervous system of the organism, 5 ~ coelenteric nerve-cell system.

nervous system. However, as opposed to the greatly advanced evolution of the latter, the enteric nerve-cell system remains throughout at the lowest stage of evolution. Initially, the enteric nerve-cell system is of entodermal origin and is positioned intra-epithelially; later, its origin is ectodermal and it is located sub-epithelially. Its nerve cells, and then the nerve-cell groups, are more or less evenly distributed in the wall of the alimentary canal. The enteric nerve-cell system is not confined to the wall of the alimentary canal; it can also be found in the walls of diverticula that develop from the alimentary canal at various periods (,hepatic ,~verticu`hma, bile duets and gall-bladder, respiratory apparatus, etc.). The at first purely afferent nerve-cell system becomes more and more efferent during phylo- genesis; the new parts of the nerve-cell system (ggl. submandibulare, oticum, pterygopalatinum) which develop in connection with the accessory digestive organs that appear later (salivary glands), consist exclusively of efferent nerve cells. The nerve fibres that originate from the enteric nerve-cell system ensure the innervation of the wall of the alimentary canal and its diverticula.

Phylogenetic Evolution of the Vegetative Nervous System 345

b) The vascular nerve-cell system is the youngest part of the vegetative nerve,us system. It appears in C y c l o s ~ o ~ a and occurs, exclusively in Verte- brata, together with the cbromaffin-cell system which belongs to the internal secretion glands, and both affect the circulatory system. It is of ectodermal origin and is an efferent nerve-cell system from the start. The very first nerve cells appear dispersed among the chromaffin cells along both sides of the main vascular trunk that runs in the axis of the body. The number

>.-

F ig . 8. Scheme of the v e g e t a t i v e ne rvous sys t em by Ente ropneus ta . i ~- ep ide rmis , 2 ~ enteron, 8 ~ nerve-ce l l s t rand of the ne rvous sys tem of t he o r g a n i s m sunk into the depth , 4 ~ ne rve- cell s t r and of t he ne rvous sys tem of t he o r g a n i s m sunk into the dep th in tubu la r form, 5 ~-

d i f fuse ne rvous sys tem of the o rgan i sm, 6 ~- enter ic nerve-ce l l sys tem.

of nerve cells increases during phylogenesis; they become steadily more separated from the chromaffin cells and form nerve-cell groups - - first separate ganglia, then ganglia chains on both sides of the main vascular trunk, which divide into prevertebral and paravertebral ganglia chains in certain regions of the body during the evolutionary process.

The prevertebral ganglia usually lie close to the origin of the visceral blood vessels and not segmentally, whereas the paravertebraI ganglia are positioned segmentally at the origin of the parietal blood vessels. The sizes of the individual ganglia are proportional to the extent of the area of the blood vessels. The nerve fibres that originate from the vascular nerve-cell system primarily innervate the vessels, but along these they reach all parts of the organism and secondarily innervate those organs, apparatuses and systems which have not as yet been under the influence of nerves. The nerve fibres may also participate in the innervation of

346 J. BotAr:

those organs which have earlier received their innervation from other main components of the vegetative nervous system; thus these organs become bi-innervated.

c) At a certain stage of development of the nervous system of the organism in Chordata and Vertebrata, it sends nerves, apar t from the animal life-function systems, to apparatuses and systems that part icipate in vege-

Fig . 4. Scheme of the vege ta t ive nervous system by Cherdata . 1 ---- central nervous system of the organism, 2 ~ main vascular trunk, 8 ---- efferent nerve fibres of the visceral nerves, 4 enteron, 5 ---- epidermis, 6 --~ afferent nerve fibres of the visceral nerves, 7 ~ enteric nerve-cel l

system, 8 ~- visceral musculature.

tative life functions - - irrespective of whether or not these have a nerve- cell system of their own. The very first visceral nerves turn natural ly toward the digestive apparatus, which develops first, and their numbers increase in accordance with the phylogenetical evolution of the digestive apparatus. Later, after the appearance of newer apparatuses and systems, the nervous system sends newer and newer visceral nerves and nerve branches to them. The afferent fibres in the visceral nerves and nerve branches run to the central nervous system of the organism. Some of the efferent fibres end at the ganglia ceils of the enteric and vascular

Phylogenetie Evolution of the Vegetative Nervous System 347

nerve-cell system. As a result of these facts, the regulation of the apparatuses and systems which participate in the vegetative life function comes more and more under the influence of the nervous system of the organism.

w Those multi-celled animals which lead to man consist of three groups.

Within one and the same group, both the nervous system of the organism

Fig . 5. Scheme of the vege ta t ive nervous system by Vertebrata. 1 = central nervous system of tho organism, 2 --~ main vascular trunk, 3 ~ efferent nerve fibres of the visceral nerves, 4 enteron, 5 ~ epidermis, 6 ~ vascular nerve-cel l system and chromaffin-eel l system, 7 ---- af- ferent nerve fibres of the visceral nerves, 8 = enterle nerve-cel l system, 9 ~-- visceral muscu-

lature.

and the vegetative nervous system are essentially similar, and each re- presents a stage of its phylogenetic evolution.

1. In the large group that comprises Coelenterata, Echinodermata and Protochordata (Figs. 2 and 3), the nervous system of the organism is diffuse; intraepithelial nerve-cell strands develop in the main lines of the organism and the first signs of the deep sinkage of the former appear. Only the enteric nerve-cell system of the vegetative nervous system is present; it is diffuse, situated intraepithelially and afferent.

348 J. Bot~ir:

2. In the small group comprising the Chordata (Fig. 4), the nervous system of the organism has concentrated in the nerve-cell strands that run in the dorsal median line, and has sunk deeply in a tubular shape; this neural tube forms the central nervous system, and the peripheric nerves appear. Two main constituents of the vegetative nervous system are now present. Beside the mainly afferent, but subepithelially positioned, diffuse enteric nerve-cell system, the visceral branches of the peripheric nerves appear which innervate the digestive apparatus that developed first.

8. In the large group that consists of all the Vertebrata (Fig. 5), the cerebrum develops in the anterior part of the neural tube, simultaneously with the sense organs on the anterior pole of the organism. All three main components of the vegetative nervous system are present. The enteric nerve-cell system accumulates in subepithelial ganglia and its nerve cells gradually take on an efferent character. The efferent vascular nerve-cell system appears, and develops more and more. The visceral nerves and nerve branches of the nervous system o,f the organism innervate first the digestive apparattts and than the apparatuses and systems that have appeared later; some of their nerve fibres becoane connected with the enterie and vascular nerve-eeU system.

w The phylogenesis of the vegetative nervous system, as outlined above,

is in agreement with our present knowledge concerning its ontogenesis, m o r p h o l o g y and physiology. Moreover, it facilitates a bet ter recognition of the vegetative nervous system and its parts as well as its classification on a morphological basis.

Summary �9

The classification of the vegetative nervous system needs a radical change, ac- cording to phylogenetic investigation as a result of recent zoological informations.

The enteric and vascular nervous system, and the visceral part of the nervous system of the organism belong to the great vegetative nervous system. The enteric nervous system is the oldest, phylogenetieally, it appears in Coelenterata and is present in all animals. The vascular nervous system is the youngest, it appears in Cyclostomata and is only present in Vertebrata. The nervous system of the organism first sends visceral nerves to the viscera in Chordata; these nerves and nerve branches are multiplied in Vertebrata.

Zusammenfassung Die Aufteflung des vegetativen Nerveusystems erfordert angesichts der auf neuen

zoologischen Befunden benLhenden phylogenetischen Untersuchungsergebnisse eine tiefgreffende Nnderung.

Zum groBen vegetativen Nerveusystem rechnen das enterale Nerveusystem, das vaskul~ire Nervensystem sowie der viszerale Tefl des Nervensystems des Organismus. Phylogenetisch am gltesten ist das enterale Nervensystem, das berelts bei den Coel- enteraten erseheint und bei s~imtlichen Tieren angetroffen werden karm. Am jiing- sten ist das vaskul~ire Nervensystem, das bei den Cyelostomen erscheint und nur bei den Vertebraten vorkommt. Das Nervensystem des Organismus schiekt zuerst bei den Chordaten viszerale Nerven zu den Eingeweiden; diese Nerven und Ner- venzweige vermehren sich bei den Vertebraten.

Phylogenetie Evolution of the Vegetative Nervous System 349

R4sum6

Les r6sultats des reeherches phylog6n6tiques, fond6s sur les donn6es r6eentes de la zoologie, n6eessitent une nouvelle subdivision du syst6mo nerveux v6g6tatif.

Suivant la nouvelle subdivision, au grand syst6me nerveux v6g6tatif appartien- nent le syst6me nerveux ent6rique, le syst6me nerveux vaseulaire, aiusi que ]a partie vise6rale du syst6me nervenx de l'organisme. Au point de vue de la phylogen6se, le plus ancien est le syst6me nerveux ent6rique qui apparalt d6ja dans les Coelent6r6s et qui se retrouve claus tousles animaux. Le plus r6eent est ]e syst6me nerveux vaseu- laire qui apparait darts les Cyelostomes et qui ne se rencontre que dans les Vert6- br6s. C'est dam les Chord6s que le syst6me nerveux de l'organisme envoie pour la premi6re lois des neffs vise6ranx anx vise6res; ees neffs s'augmentent en nombre dans les Vert6br6s.

Bibliography Kuntz, A., The evolution of the sympathetic nervous system in Vertebrates. J.

Comp. Neurol., Philadelphia, 21 (1911), 215--286. - - Gaskell, W. H., The involun- tary nervous system. Longmans, Green and Co., London-New York, 1916, 1920. - - Kuhlenbeck, H., Betrachtungen tiber den funktionellen Bauplan des Zentralnerven- Systems. Fol. anat. Jap. 4 (1926), 111--185. - - Goodrich, E. S., The problem of the sympathetic nervous system from the morphological point of view, Comp. rend. Ass. anat. 22 (1927), 103---104. - - Goodrich, E. S., Studies on the structure and develop- ment of Vertebrates. Macmillan and Co., London, 1980. - - Ari~ns Kappers, C. U., Anatomie eompar6e du syst6me nerveux. De Erven F. Bohn and Masson & Cie., Haarlem-Paris, 1947. - - Nicol, J. A. C., Autonomic nervous system in lower Verte- brates. Biol. Rev. 27 (1952), 1---49. - - Pick, 1., The evolution of homeostasis. Proc. Amer. Phil. Soe. 98 (1954)~ 298--803. - - Vandel, A., L'origine des Vert6br6s. Ann6e biol., Paris, III, 87 (1961), 5--41.

Ansehrift des Veffassers: Prof. Dr. ]. Botdr, Budapest, Posta 27/1 (Ungarn).