This is a subject upon which most authorities differ widely, and few, if any, agree upon all points entirely. It is therefore, an inviting field tor research. Because of the extreme diversity of opinions current it has seemed best to me to formulate them in a brief way before giving the results of my own observations

Place, B. A.

English

University of Northern Iowa

Proceedings of the Iowa Academy of Science Volume 13 Annual Issue Article 40 1906 Relation of the Motor Nerve Endings to Voluntary Muscle in the Frog B. A. Place Copyright ©1906 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Place, B. A. (1906) "Relation of the Motor Nerve Endings to Voluntary Muscle in the Frog," Proceedings of the Iowa Academy of Science, 13(1), 261-266. Available at: https://scholarworks.uni.edu/pias/vol13/iss1/40 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. • RELATION 01<' 'fHE IIIOTOR NERVE ENDINGS 'fO VOLUNTARY MUSCLE IN THE FROG. BY B. A. PLACE. Plate XXVIII. This is a subject upon which most authorities differ widely, and few, ii any, agree upo11 all points entirely. It is therdore, an inviting field tor research. Because oI the extreme diversity of opinions current it has seemed best to me to formulate them in a brief way before giving the results of my own observations. Jt seems to be generally agreed that there are at least some nerve endings distributed to every voluntary muscle fibre. As nothing to the contrary has been found in my work this matter will not be referred to again in this paper. Th<) points on \\·hich difference of Opinion are based are as follows, and will be discussed in the same order. (1). Is there an end plate or localized accumulation of specialized muscular tissue in which the branch·es of the axis-cylinder terminate? (2). What is the relalion of the ultimate branches of the axis-cylinder to the sarco-lemma? (3). Where does the sheath of H,'nle stop, also the medullary sheath and the ncurilemma? ( 4). What is the appearance and disposi-tion of the ultimate branches of the axis-cylind·er '? The Huber-Dewitt paper states that "Kiihne deserves the credit of the discovery that th·.!' axis-cylinder terminates under the sarcolemma in the nucleated granular substance which he describes as the sole l Sohle) ; the nuclei as sole nuclei ( Sohlenkernc) ··. It also states that Kuhne mal;es the hypothesis that the sole is "muscle protoplasm sar-coglia or sarcoplasm, while the nuclei of the sole might be likened to muscle nuclei". To quote them still further: "This interpretation of the granular sole and its nuclei suggested itself to us before Kii'hne's similar observation was definitely understood." They add this feature to its description: "As is well known in Amphibia, the axis-cylinder of the motor fibre terminating in strip_,d muscle does not end in a localized area (birds, reptilia and mammalia), but ramifies over a proportionately much larger area. Conditions. here presented are therefore very similar to those in such as present a localized motorial ending with the distinc-tion that in the later the axis-cylinder terminates in a localized elevation-,;. the sole-which has been interpreted as a circumscribed accumulation of sarcoplasm surrounding the ramified ending of the axis-cylinder and extending like it over a larger proportionate area of the muscle fibre:· ·wnson makes this statemc>nt denying the existence of any ground plate at all: "In the frog's muscle the nerve ·.:nding has no ground plate in (261) 1Place: Relation of the Motor Nerve Endings to Voluntary Muscle in the FrPublished by UNI ScholarWorks, 1906282 IOWA ACADEMY OF SCIENCES which the branches ramify.'' Sihler thinks that what has been seen in this regard by Kuhne and others is derived from H~nle's sheath. To quote: "I find that the so-called 'Sohlenstanz' of Kuhne is derived from Henle's sheath." Huber-Dewitt conclude that the end branches of the axis-cylinder are entirely under the sarcolemma. To use their own language: "Two cross sections are shown in Figs. 13 and 14. It may here be se·en that the ramifications of the axis-cylinder are under the sarcolemma termin-ating in a relatively thin layer of sarcoplasma." Kuhn·e is mentioned by them as holuing a similar view. According to Sihler, Engelmann, Klein, Gerlach, Frey, and Waldeyer are also of this same opinion. Sihler him-self, howev.,~r. concludes that with perhaps some qualifications these end-branches are epilemmal. The following statements from him will serve to show his position: "The endings of motor nerves in striped muscle r<'main on the outside of the sarcolemma. What may be the exact con-dition of things at the points where muscle and nerve fibre are in actual contact-whether the sarcolemma and neurilemma are wanting there or perforations exist-I cannot say. The precise relation of muscle to nerve here is an unsolved and difficult problem." Dogie! in the following language states that the~- are hypolemmal "die l\Iarksubstanz aber sammt dem Achsencylinder tritt unter das Sarcolemma". Huber-Dewitt quote Rhetzius as being in doubt whether the end branches are epi- or hypo-lemmal. Wilson takes the view that th·,• larger branches of the endings lie over the sarcolemma and at some distance from it, while small fibril-tae possessing a terminal knob come off lying eith't•r within or under the sarcolemma. Sihl•er statPs that Renie's sheath ends before the muscle fibre is reached and is open so that the axis-cylinder with its neurilemma appears like an arm emerging from a sleeve, while the sheath of Schwan covers the end fibres down to their tips and is provided with nuclei. Huber-Dewitt thinks that the sarcol'<'mma and neurilemma become continuous with each other at the point where the nerve fibre, as they claim, pierces the sarcolemma. This small area mad·,• up of both sheaths they call telolemma and its nuclei if any are found at this point, telolemma nuclei. The following statement from Dogie! will show his attitude: "In ersten Falle tritt die markhaltige Nervenfaser an irgend eine Stelle der Muskelfaser heran, verliert in dPm Sarkolemma ihre Schwan, 'sche und Henlische SchPide" which practically agrees with thP last preceding writer. As to the appearance and disposition of these ultimate branches, Dogie! thinks they are d·2void of any sheath, are thickened, toothed and run along the muscle fibre frequently ending in a knob. He thinks thev neither go to any neighboring muscle fibres nor form any plexuses. Wilson thinks on the other hand that they are covered by a sort of a sheath fo!'med from the ordinary nerve coverings and the sarcolemma,but are non-medullated. He also thinks that some of them end in the inter-muscular connectivP tissue, and that othNs go to neighboring fibres. Plexuses are found at times also, he thinks. Sihler remarks that the ,. 2Proceedings of the Iowa Academy of Science, Vol. 13 [1906], No. 1, Art. 40https://scholarworks.uni.edu/pias/vol13/iss1/40.. IOWA AOADEMY OF SCIENCES 263 nuclei of the neurilemma on the~e fibrils have more of a tendency to roundness and that the individual fibrils en<! as such and not in a bulb. He states that the endings have little of the medullary sheath. This investigation was begun in 1904, and was presented in somewhat different form to the faculty of Ohio University in June, 1905, as a thesis for the degree of A. Ill. Research has been continued since then as time would permit. Th·e animal thus far used for observation was the common North American toad (B11 fo lentiginosus) and the methocl employed essentially that of Sihli'; ·,,. The microscope chiefiy used has a 2:eiss aprochromatic oil immersion t\\ o millimeter lens. Fresh tissue "as macerated, stained, teased, and mounted in glycer-ine on slides. The macerating fluid is made as follows: Ordinary acetic acid ..................................... 1 part Glycerine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... l part Chloral hydrate 1 per cent. solution in distilled water ...... G parts The mu~cles should be in lrnndles of not more than three or four millimeters in diameter. Those of the foot or tore limb of the toad or frog are already of convenient size. The staining material is prepared as follows: Well ripened Erlich"s Haematoxylin ...................... 1 part G lyc2rine ................................................ 1 part Chloral 1 per cent. solution in tlistilled \Yater ............. 6 parts The muscle should be macerated from 12 to 20 hours depending upon the age of the animal. It would do no harm to. USl' stronger acetic acid for older animals. The object is to dissolve the inter-muscular connec-tive tissue, which is accomplished when the muscle no longer offers much resistance to teasing. One should begin testing the matter as soon as 12 hours have passed. When properly macerated the tissue should be left in glycerine until it becomes saturated, which requires about t\YO hours. Before putting the tissut'. into the staining fluid it should be further teased into bundles noL more than on«~ or two millimeters in diameter. All teasing should be done in glycerine. Staining requirps from 3 to 10 days. When properly stained the muscle fibres haYc a color ranging from wine color to nearly black. Nervous and muscular material ar<' stainecl almost black, \Yhile connective tissue remains quite pale. The darkened nuclei of the capillari<'s which are everywhere so abundant are a good ind~x to the intC'nsity of the staining proeess, since nerve struc-tures take the stain at about the same rate with them. All the parts do not stain uniformly. Parts that are over-stained can be readily reduced in color by subjecting them to a w·,•ak solution of acetic acid. A con· venient way· to accomplish this is to immerse them in glycerine, to which has been added a small amount of acetic acid. The stained tissue may be k<•pt unchanged almost indefinitely in glycerine. A convenient way to find nerve structure is to tease quite a number of muscle bundles still smaller until each remaining part contains per-haps half a dozen fibres. Tlwse in a shallow glass dish may be examined 3Place: Relation of the Motor Nerve Endings to Voluntary Muscle in the FrPublished by UNI ScholarWorks, 1906264 lOWA ACADEMY OF SCIENCES under 50 to 100 diameters and the ones best showing nerve structures sorted out. These latter mounted in glycerine on slid·es will :flatten out under slight pressure upon the cover glass so as to enable one to con-tinue the ·examination with higher power of the microscope. These structures are quite delicate and when once mounted cannot be further manipulated for different views. For this reas·on there is an advantage in mounting material between large cover glai:.ses iii as much as both sides of the preparation may then be vi·ewed. There is this disadvantage, however, that such a preparation cannot be preserved long. In addition to the above process stained tissue was hard·ened in alco-hol, embedded in paraffin, sectioned and examined in series. Variolll" counter stains were ·employed but with very little success thus far. As to my own results I am. convinced that the primary nerve fibre neither terminates in an end or ground plate, or granular sole, nor pierc'eS the sarcolemma, at least at that point. It would seem to me that the sole nuclei d·escribed by Huber-Dewitt and others were end bulbs belong· Ing to the ultimate branches of the axis-cylinder. For by this method unless a particular preparation is stained quite perfectly only a few of the end fibrils can b'e traced, while tpeir granular nuclear-app~aring bunches or knobs appear quite conspicuous, but disconnected. I was for some time of the opinion myself that these apparently isolated knobs belonged to th·e muscle fibre, and that the muscle fibre was consequently specialized at these places for receiving the nerve endings. But by observing that the best stained preparations showed all of these knobs or bulbs to be either connected, or partly so, by fine nerve fibrils, I con-cluded that such would be the case with all of them if th·e staining was sufficiently perfect. Later observations confirm the belief. There seems to oo no regular order, size, shape or number ·Of either the end fibrils or end bulbs. Generally the fibrils are relatively short and the bulbs are elongated and more pointed at the distal ends. Plexuses among the fibrils are occasionally found. The fibrils show by their pale outline down to their tips a covering of connective tissue which is probably a continuation of the neurilemma. In my ·Observation .no neurilemma nuclei have been seen upon them, but this does not argue much for the absence of neurilemma here, in as much as neurilemma nuclei of the main fibre are generally much farther apart than the entire length of these fibrils. These structures seem to be connected more or less with the sarcolemma, as may be se·,m by their adhesion to that membrane when being torn off. The relation sN•ms to be either that of intermuscu-lar connective tissue joining fibrils and bulbs to th·e sarcolemma, or a superficial coalescence between neurilemma and sarcolemma. In the examination of a very great numoor of cross and longitudinal sections no point could be found where either bulbs or fibrils were beneath the sarcolemma. In the fibrils the medullary sh·eath is either present in very slight amount or is entirely wanting. l!~igure 1 is fairly typical of this structure. Exceptional forms are occasionally found differing widely from the typical. .. .. ·• .,. 4Proceedings of the Iowa Academy of Science, Vol. 13 [1906], No. 1, Art. 40https://scholarworks.uni.edu/pias/vol13/iss1/40• IOWA ACADEMY OF SCIENCES 265 The sheath of Henle is a rath·dr robust structure of the primary nerve fibre presenting nuclei similar to those of the neurilemma. The nuclei of neither of thes·c) structures seem to have any regular order or position. These two sheaths appear to coalesce at, or slightly distal to, the point where the axis-cylinder breaks up into its fibrils. More evidence, how-ever, is desirable upon this point. The myelin or medullary sheath stains dark, about the same) as the axis-cylinder, which \Yould tend to show that this structure was nervous and not connective tissue, Inci· dentally this helps to settle the question-from what is the myeline sheath deriV'c)d, whether from the axis-cylinder or from the sheath of Schwann? It is wanting, or nearly so, at intervals known as nodes of Ranvier. Divisio;is of the axis-cylinder occur at these nodes. These structures are shown in Figure 2. Piersol. Dogid. Sihler. Sihler. Sihler. Sihler. Sillier. WORKS CONSULTED. Normal Histology. Methylenblautinktioh der motorischen Nervenendigungen in den Muskel der Amphibien und Reptilien. Archiv fur Mikroskopische Anatomie. 1890. On the Endings of the Motor Ne:rves in the Voluntary Muscle of the l<~rog. Studies from the Biological Labora-tory of Johns-Hopkins University, Vol. III, 1885. Neu Untersuchungen u·ber die Nerven der Muskeln mit besonder Borucksichtigung umstreittener Fragen. Zeit-schrift fiir wissenschaftliche Zoologie. LXVIII. 3 . The nerves of the Capillaries with remarks on Nerve-endings in Muscle. Journal of Experimental M'edicine. Vol. V, No. 5. Verbandlugen der physiologischen Gesellschaft. rung, 1894-5. Jah-Die Muskelspindeln, K·t!rne und Lage der motorischen Nervenendigungen. Archiv fur microskopische Anatomie und Entwicklungsgeschichte. Band. 56. 1900. Huber-Dewitt. A contribution on the Motor Nerve-endings and on the Nervt!-endings in the Muscle-spindles. Journal of Com-parative Neurology, March, 1898. Wilson. The Relation of Motor Endings on the Muscle of the Frog to the Neighboring Structures. Journal of Compar-ative Neurology and Psychology, March, 1904. KEY TO THE DRA. WINGS. A and B, muscle fibres. a and a' , nerve fibres. c and d, branchings other than at points where the axis-cylinder IJreahs up into its ultimate fibrils. b-The point where the nerve fibre brt)aks up into its ultimate fibrils, which is usual soon aftt;r the primary fibre comes upon the muscle fibre. 5Place: Relation of the Motor Nerve Endings to Voluntary Muscle in the FrPublished by UNI ScholarWorks, 1906266 IOWA ACADEMY OF SCIENCES Med. S.-Medullary sheath. Axis-C.-Axis-cylind·"r. N eu.-N eurilenima. Hen.-Henle's sheath. Hen.-N.-Nuclei of Renie's sheath . End. f.-End fibrils. End. b.-End bulbs. Plex.-Plexus. The size of the fibres are exaggerated. ., " 6Proceedings of the Iowa Academy of Science, Vol. 13 [1906], No. 1, Art. 40https://scholarworks.uni.edu/pias/vol13/iss1/40

Relation of the Motor Nerve Endings to Voluntary Muscle in the Frog

https://scholarworks.uni.edu/cgi/viewcontent.cgi?article=6977&context=pias

Relation of the Motor Nerve Endings to Voluntary Muscle in the Frog

Abstract

Similar works

Full text

Available Versions

University of Northern Iowa