Paper - On the origin of the lymphatics in the liver (1901)

From Embryology
Revision as of 13:07, 18 February 2020 by Z8600021 (talk | contribs)
Embryology - 3 Apr 2020    Facebook link Pinterest link Twitter link  Expand to Translate  
Google Translate - select your language from the list shown below (this will open a new external page)

العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

Mall FP. On the origin of the lymphatics in the liver. (1901) Johns Hopkins Hospital Bulletin 12: 140

Historic Disclaimer - information about historic embryology pages 
Mark Hill.jpg
Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

On the Origin of the Lymphatics in the Liver

Franklin Mall (1911)
Franklin Mall

By Franklin P. Mall.

Professor of Anatomy, Johns Hopkins University.


Introduction

The origin of the lymphatics of the liver was first deiinitely determined hy MacGillavry," who studied this subject under the direction of Ludwig. Long before the work of Macrjillavry it had been observed that ligature of the bile duct was followed by passage of bile over into the lymphatics, and the artificial filling of the lymphatics naturally followed by injecting a colored fluid into the bile duct. Sections of liver, in which the lymiihatics had been filled with Prussian blue, or with as]ihaH, showed that the fluid injected into the bile ducts leaves them at the periphery of the lobule to enter spaces surrounding the blood capillaries, the so-called perivascular lymph spaces. These spaces communicate at the ]ieriphery of the lol)ule directly with the interlobular lymph channels. Frequeiitly there is an extrava.«ation of the injection mass into the blood capillaries of the lobule.

These observations were subsequently confirmed by numerous competent investigator.?, using the method employed by MacGillavry as well as that of direct injection of Prussian bhie into the walls of the portal and hepatic veins. In successful injections made in this way it is found that the Prussian blue injected enters the lobule to encircle its blood capillaries." Such injections, however, are always accompanied with numerous extravasations of the injected material into the tissues ])etween the lobules, and often there is a secondary injection into the blood cajiillaries of the lobule. This fact has raised an objection to the dii-ect injection of the lymphatics from the bile capillaries. It appears more probable, the opponents say, that the extravasation of bile, or the injected material into the interlobular spaces, enters the lymphatic radicals of the capsule of Glisson, and from them the larger lymph cliannels and the perivascular spaces of the capillaries are tilled. Furthermore the injected mass may pass from the pericapillary spaces directly into the capillaries, thus accounting for their frequent injection.

According to Fleischl,' all tlie bile is taken up by the lymphatics after ligature of the bile duct, and in case the thoracic duct is also ligated no bile or only a trace of bile ever reaches the blood. The observation of Fleischl has been confirmed by Kunkel,' Kufferath ° and Harley." It is extremely difficult to understand why the bile does not enter the blood capillaries in case it passes from the bile capillaries over into the perivascular spaces before it reaches the interlobidar spaces after ligature of the bile duct. A further objection to the idea that the perivascular spaces first take up the bile, after ligature of the duct, is the fact that fluids


1 MacGillavry, Wiener Sitzungsber., 1SG4. - Budge, Ludwig's Arbeiten, 187.5. 3 Fleischl, Ludwig's Arbeiten, 1874. ■> Kuukel, Ludwig's Arbeiten, 187.5. !• Kutlenitb, Arch, fur Pbysiol., 1880. "llarlcy, Arcliiv fiir Physiol., 1SH3.


injected into the bile duct pass with ease over into the lymphatics but only with difficulty into the bile capillaries. In all cases it appears as if the main origin of the lymphatics is at the periphery of the lobule and that the radicals communicate freely with the perivascular lymph spaces. Furthermore, it appears that the course the bile takes after ligature of the bile duet, or of a fluid injected into the bile duct in passing to the lymphatics, is between the lobules or at least at their extreme periphery. This idea is greatly strengthened since we know that the walls of the capillaries of the lobule are extremely porous, being composed of a dense layer of reticulum fibrils ' upon which lie the endothelial or Kupfl'er's cells. This layer of reticulum fibrils encircling each capillary has been described from time to time by many investigators, and has been isolated by Oppel ° and by myself.' Oppel obtained clear pictures of the connective tissue of the liver lobule by means of silver ])recipitatioii, while I employed Kiihne's method of pancreatic digestion to remove the cells, followed by some intense stain like acid fuchsin. The nature of theso fibrils is still under discussion but that matters little for the present communication. It is sufficient to know that flic fibrils of reticulum form a basket-like membrane surrounding each capillary of the whole lobule, the interior of which is only partly lined by Kupffer's syncytial endothelial cells. The capillary walls then are very pervious, blood plasma passing easily from them out into the perivascular spaces to bathe the liver cells.

It is well known that a large quantity of lymph is constantly passing from the liver, much more than from any other organ. That this lymph comes directly from the blood is indicated by its high per cent of proteid matter, nearly that of the blood, and from two to three times that of the lymph from other parts of the body.

The course the lymph takes from the blood to the lymph radicals, i. e. its natural course, can easily be marked by injecting colored gelatin into any of the blood-vessels. 1 have usually found it most convenient to inject the gelatin into the portal vein, but it is just as easy to fill the lymphatics by injecting either the hepatic artery or hejiatic vein. In all cases the colored fluid reaches the main lymph channels in the same way. The colored gelatin flows with great ease from the capillaries at the periphery of the lobule as well as from those around the sublobular vein into the lymphatics. After the lymphatics have all been filled it is well to inject a small quantity of fluid of different color into the bloodvessels. A much better method of making double injections is to mix red granules with a blue gelatin or blue granules


1 Kupffer, Arch. f. Mik. Anat., ^4.

•* Oppel, Arch. Anz., 1890.

'Mall, Abhaudl. d. K. S. Ges. d. Wiss., .xvii, 1891,


April-May-June, 1901.]


JOHNS HOPKINS HOSPITAL BULLETIN.


147


with a red gelatin, the fenestrated lining membrane of the capillary acting is a sieve which allows the fluid to pass but holds back the granules, as is the case with the blood wheu normal circulation is taking place.

If the portal vein is injected with Prussian-blue gelatin under a low pressure, it is found that in a few minutes the lymphatics are all filled with the blue mass. Jjivers injected in this way are best hardened in formalin and then cut by tJU' freezing method, for alcohol causes the gelatin to shrink. Such sections show that the blue fluid has entered the lym|)haties at the periphery of the lobule. More instructive arc the specimens when the injection is stopped just as the first lymjihatics are filled with the colored gelatin. By following the larger lymphatics back into the liver substance it is found that the interlobular connective tissue is entirely filled with blue where the lymjihatics are injected, but only partly colored blue when they are not. In other words, the blue extra ■-■ - • /©./ L



Fig. 1. — Section throuj^h tlie periphery of the liver lobule of a cat. The hepatic artery was iujecteii with cinnabar gelatin, ami the portal vein with Prussian-blue gelatin, stained with Van Gieson's stain, x .500 L, lobule of liver ; <■, oapillarios ; a, artery; ?, lymph vessel; pi'l, times, perivascular lymph space ; pW, perilobular lymph space; w, bundles of fibrils of white tlbrous tissue.

vasates from the jieriphery of the lobule, invades the connective tissue until it reaches the beginning of the lymphatics, when of course it is carried rapidly from the liver. The nearest course from the lobules to the lymphatics is between the lobule where the amount of connective tissue is small, so when colored fluid is beginning to enter lymph channels the tips of the capsule of Glisson are entirely colored, while larger portal spaces are encircled by a zone of the color. Furtliermore it is found that in certain instances when the injection was not continued long enougii tlie libu^ did not enter the lymphatics. In such specimens it is found that all the interlobular spaces are surrounded by a zone of colored gelatin which does not enter the main lymjih channels.

A successful injection of the lymphatics is illustrated in the accompanying figure. The section was stained with Van Gieson's stain which gives a very satisfactory result. The granular blue enters the capillaries of the lobule, c, with ease.


and from them the liquid blue is filtered through the capillary walls to enter the perivascular lymph space. This space communicates at the periphery of the lobule directly with a large lymph space between the liver cells and the capsule ot Glisson, which I shall term the perilobular lymph space. These spaces in turn communicate with the lymph radicals.

Injection of the blood-vessels of tlie liver with aqueous Prussian blue fills the capillaries only, and in all cases it is shown that there are no capillaries between the periphery of the lobule and the interlobular connective tissue. The liver cells come directly against the capside of Glisson. An injection of brief duration with blue gelatin soon fills the perilobular lym])h spaces, so that it appears as if all groups of liver cells at the periphery of the lobule were separated from the interlobular connective tissue with capillaries. In ease cinnabar granules are mixed with the blue a few of these granules are found in the perivascular and perilobular lymph spaces. The openings in the walls of the capillaries are large enoiigh to allow a few of the smaller granules to pass through. As the injection is continued the blue invades the connective tissue spaces from the lymphatic radicals more and more until a lymph channel is reached, when of course it flows rapidly from the liver. -Were there a direct channel from the perilobular lymph spaces the blue should flow through it at once without further filtration through the interlobular connective tissue spaces. The course the cinnabar granules take also speaks against a direct channel between the perilobular lymph spaces and the interlobular lymph channels. A few of the granules enter the ]ierilolnilar lymph sjiaces, but none of them reach the main lymph channels. All of my specimens without exception force me to the conclusion that there are no direct channels connecting the perivascular and perilobular lymph spaces with the lymphatics proper other than the ordinary spaces between the connective-tissue fibrils of the capsule of Glisson. These spaces, however, are relatively large, permitting of a rapid diffusion through them.

Interstitial injections into the walls of the interlobular veins natui-ally liU the surrounding lymphatic vessels, and when no valves are in the way the injected fluid passes to the origin of the vessels, or lacunte, which are only in part lined with endothelial cells. From here the fluid passes through the main connective-tissue spaces to the periphery of the lobule into the perilobular and perivascular lymph spaces, and frequently from thtm into the blood capillaries. When the injection is made through the bile ducts I have always found that there is an extravasation of the fluid from these at the periphery of tlie lobule which immediately enters the lymph radicals, although the bile capillaries are often injected well into the lobule. The extravasation docs not take place from the bile capillaries, only from the duct as it communicates _with the capillaries; also it does not take place from the larger bile ducts. Such extravasations naturally are picked up by the lymphatics and are at once carried from the liver. If after ligature of the bile duct the bile enters the perivascular lymph space within the lobule it may still be carried to the


148


JOHNS HOPKINS HOSPITAL BULLETIN.


[Nos. 131-122-123.


lymphatics, as the direction of the current of lymph is constantly from the blood capillaries to the lymphatics.

It is well known that the liver cells arise from the enibiyonic bile dncts. and that in the further growth of the liver the bile ducts must elongate in order to adjust themselves with the growing liver. Hendrickson '° has shown by staining the bile capillaries and ducts of tlie embryo's liver by Golgi"s method that the tip of the primitive l)ile duct is added to by a coalescence of the bile capillaries at the periphery of the embryonic liver lobule. My own observation on the liver lobule after it is well formed is that whenever karyokinetic cell figures are present they are at the periphery of the liver lobule, i. e. at the junction of the bile capillary with the bile duct. It also appears that the vascular walls of the embryo are much more pervious than those of the adult. Judging by the ease extravasation takes place when the blood-vessels of embryos are injected. This observation taken with that ol the growth of the bile ducts may be an explanation why the e.xtravasation of a fluid injected into the bile duct takes place at the periphery of the lol)ule. A further hint in this direction is the observation that it is easy to inject the lymphatics from the blood-vessels of an inflamed area. I have often seen the lymphatics of an inflamed intestine filled with blood, and upon injecting the blood-vessels found that the fluid readily entered the lymphatics."


'"Hendrickson, Johns Hopkins Hospital Bulletin, 1898. " See also Sigmund Mayer, Anat. Anz., 1.S99.


That the capillaries of the liver communicate more freely with the lymphatics than do the bile ducts is jiroved by injecting the bile duct and the portal vein with fluids of different color under the same pressure at the same time. In all the experiments I made the fluid injected into the vein appeared in the lymphatics first. In many instances beautiful injections of the lymphatics were obtained from the vein while the fluid injected into the bile duct did not extravasate at all, showing at least that the veins communicate with the lymphatics much more freely than do the bile duets.

The conclusions to be drawn from the above observations are (1) that the lymphatics of the liver arise from the perilobular lymph spaces and that these communicate directly with the perivasculai" lymph spaces; and (2) that the lymph reaches these spaces by a process of filtration through openings which are normally present in the ca|)illary walls of the liver. Fiirthermore, the fluid injected into the lymphatics from the bile duct leaves the duct as it enters tlie lobule and is at once taken up by the lymph radicals and perilobular lymph spaces, and from tliem extends, as a secondary injection, to the perivascular lymph spaces, and often into the blood capillaries of the lobule. The larger lymphatics accompanying the portal vein arise between the lobules near their bases, while those accompanying the hepatic vein do not arise within the lobule but around the larger sublobular veins.


BORN'S METHOD OF RECONSTRUCTION BY MEANS OF WAX PLATES AS USED IN THE ANATOMICAL LABORATORY OF THE JOHNS HOPKINS UNIVERSITY.

By Chahles Eussell Bakdeen, Associate in Anatomy, Johns Hopkins University.


The wax-plate method of reconstruction (Plattenmodellen methode) described by Born in 1876 ' has proved of great value in the study of the morphology of embryos. The method has received its most extensive application in the hands of Born, of His and of various pupils of these investigators. In general, however, it may be said, that the value of this method as an aid to the microscopic study of form has not been sufficiently appreciated.

In part this lack of a more general application of the method has been due to certain technical difficulties which tend to make it cumbersome and time-consuming. Yet by no other method can so accurate an idea be obtained of the form of those structures which from their minuteness or complexity of relation cannot well be dissected out.

Considerable application of the method has recently been made by different persons in this institution and each worker has contributed something towards making the method more effective.


I Morph. Jahrb. II; Arch. f. mikr. Anat., xxii, p. 584.


As originally described by Born several steps are essential for the successful application of his method. These may be tabulated as follows:

A. Preliminary steps.

1. Obtaining a good picture of the embryo or object to be reconstructed.

2. Hardening, staining and sectioning the object.

3. Drawing magnified enlargements of the sections or such parts of them as it is desired to reconstruct.

4. Preparation of the wax plates.

5. Transference of the image to the surface of the wax and cutting out the wax plates.

B. Constructing the model.

1. Piling the wax plates.

2. Removing parts not essential to the reconstruction desired and rounding oft' of the parts reconstructed.

3. Strengthening and finishing the model.

I shall consider these steps in the order named.

A. Preliminary steps.

1. Before proceeding to section the object to be recon


April-May-June, 1901.]


JOHNS HOPKINS HOSPITAL BULLETIN.


Ui)


structed it is important to obtain good pictures of its external form. With such a picture at hand it is much easier to pile up the wax plates which represent the sections through the object. This is especially true when the object is symmetrical, as in the reconstruction of embryos, profile views of which are invaluable in this work. If the picture be enlarged to the magnification of the model desired a valuable control is furnished. A series of parallel lines may then be drawn through the picture to represent the planes through which the knife has passed in sectioning the embryo, so that the position of every plate is indicated.

For general purposes photography is undoubtedly the most convenient method of recording the gross external features of the object. If the object be very small as, for instance, an early human embryo, the camera may be so placed that the image in the negative is enlarged from two to four diameters. It is found that the most convenient way of photographing embryos is to place the camera wdth the axis in a vertical direction and the lens pointing downwards. A stand for holding the camera in this position and raising or lowering it is easily constructed. Ordinary lead shot seems to be especially good for holding many small objects in the position in which it is desired to photograph them.

For detail in the distant as well as the proximal part oi the object it is a great aid to make use of a stand capable of being raised without moving the object laterally. In this way, if the diaphragm be closed down so as to make the exposure a long one, the object may from time to time be brought slightly nearer to the lens of the camera, so that parts more distant are brought into sharp focus.

From the photographic plates thus obtained lantern slides are made or the negative itself is used to project the imag. at the required magnification upon a screen. Free-hand drawings are then traced on a paper upon which the image falls, or, if desired, bromide enlargements can be made. In this way accurate records can quickly be made of the external appearance of the object to be studied, yet no special talent for drawing is required. In the study of embryos the jirofile view is the most essential one, though others also prove of great value.

2. The only real essentials in the technique of obtaining serial sections of the object to be studied are that the series should be complete, the sections perfect and of uniform thickness. As pointed out by Born, the most convenient sections for this work are those from 20-40 microns in thickness. For sections of this thickness we have found alum cochineal to give uniformly the most satisfactory stain. It is important to know which side of the sections was uppermost during the cutting, so that in the subsequent reconstruction a true and not a mirror image of the object will be formed. For this reason it is well to make it a uniform practice to begin at the head when cutting transverse sections through an embryo, at the right side when cutting longitudinal vertical sections, and at the dorsal side wlien cutting liorizontal sections and to label the sections in the order in which they have been cut.


3. For making drawings of the sections we have found that in general a projection apparatus is more convenient than a camera lucida unless the sections are small. Our projection ajijiaratus is set up in a large dark room.

The illumination is received from an arc electric light or from a heliostat. An ordinary microscopic stand with the tube in a horizontal direction is used when the sections are small and a high magnification is desired. Eye piece and draw tube are usually removed and the objective is used as the magnifying lens. In case of larger sections a projection lens similar to that used for lantern slides is utilized.

The image is projected upon a screen which runs on a track. The screen can be moved toward or away from the microscope by means of windlass situated near by. In this way any desired magnification can be quickly obtained by using an appropriate lens and bringing the screen into the proper position.

The screen which I devised for our dark room has attached a leaf which can be lowered so as to form a drawing table and a mirror that can be placed at an angle of 45° over the table. In this way the image is projected on a horizontal surface so that tracing it is easier than when it is upon a vertical surface. In using an ordinary mirror a double image is projected but that from the surface of the mercury is so much brighter than that from the surface of the glass that no difficulty is experienced in drawing accurate outlines.

Fig. 1 illustrates the apparatus here in use.



Fig. 1. — At the right the projection screen is shown in position on the tracli. The mirror is lowered to an angle of 45° and the drawing table is extended horizontally below this. At the left are shown the windlass used for moving the projection screen and the shelf used for holding the projection lantern.

In drawing pictures of the sections a careful outHuo of those main features which it is desired to bring out in tlu' reconstruction is the great essential. In addition it is often of value to distinguish by using pencils of various colors the different organs in structures as they appear in the section.

If desired, direct bromide enlargements can be made of the sections on the slides. This is the method preferred liy His. The simpler method described above we have found, liowever, to be more convenient for general purposes.

The outline drawings may often be elaborated to any desired extent when the sections are subjected to carefvd microscopic study. It is a great help for the subsequent reconstruction to label, so far as possible, the various structures in the outlines of the sections before proceeding to the wax plates.


150


JOHNS HOPKINS HOSPITAL BULLETIN.


[Nos. 131-122-123.


4. Much trouble in the preparation of the wax plates is to be saved by using plates of a uniform thickness and by making the magnification of the object under reconstruction correspond. The most convenient thickness for general use is 2 mm. Occasionally, for coarser work, 4 mm. plates have proved of value. It is very easy, with the apparatus above described, to make the ratio of the dianftter of magnification of the drawings to the diameter of the sections equal to that of two millimetres to the thickness of the section. If plates 2 mm. thick be used and every section be drawn, sections 20 mm. thick = 1/50 mm. must be magnified one hundred times. Or if desired, as is more often the case, every other section may be drawn at a magnification of fifty diameters.

For making the wax plates we have a large zinc pan with vertical sides. Its surface area is such that one kilogram of the wax mixture which we use will make a plate 1 mm. thick. The method of casting the plates is essentially that described by Born. Boiling water is run into the pan to the deptli of several inches. On the surface of this the hot melted wax mixture is poured and quickly forms an even, smooth, layer. Bubbles, which occasionally appear in the wax, may be quickly exploded by turning the flame of a Bunsen burner on the surface of the wax where they appear. As the wax plate cools it is necessary to free it from the sides of the pan by running a knife along the edge. Before the plates are perfectly cool they may readily be cut into smaller plates of any desired size.

The wax mixture in use here is composed of 950 parts of bees-wax and 50 parts of white rosin. Often, especially in summer, paraffin is added to give additional toughness. Black plates are made by adding lamp black to the melted wax, until after thorough stirring the mixture has become uniforndy black. The amount by weight of wax necessary for a plate of a given size is obtained more easily by experimental trial than by calculation. A certain amount of wax becomes attached to the sides of the pan by surface tension, so that slightly more wax must be used than the amount one is likely to determine by calculation from the specific gravity of the wax and the size of the ])an. On the other hand if a pan of a given size be used the amount of a given wax mixture necessary for making a plate of given thickness may be determined by a few trial castings.

The outlines are transferred to wax by means of red or blue tracing paper. The wax plates are then placed upon glass and are cut with a small, narrow knife and in a warm room.

B. Constructing the model.

1. The janitor can be trusted to trace the outline drawings on wax, to cut througli the wax with a sharp knife where the outlines are traced and to make the preliminary piling. Usually two preliminary piles are made, one of that part of the wax plates which represent the sections and one of the wax plates themselves after removal of the parts representing the sections. From the former a positive, from the latter a hollow negative image of the original object is ob


tained. In this piling an enlarged picture of the object is of very great help. As originally suggested by Born, in case of symmetrical objects a surface outline may be drawn on card board and cut out, thus giving a fixed ridge against which to pile the plates. If but one side of any embryo is to be reconstructed from transverse sections it is of great help to cut each plate off sharply at the midline and to pile the plates against a profile outline of the embryo situated on a Ijoard which has been placed ]ierpendicular to the plane in which the plates are piled. In case the reconstruction of some internal organ is wanted it is usually of advantage to reconstruct at the same time the external form of the object, so that when the jjlates are piled the iiuage they form may be compared with the picture of the original object. After getting the plates composing the positive image of the object into proper position, it is easy to trace two or three of its surface curves on paper or to represent them in wire and then to get the negative formed, as described above, into true shape. Plaster casts can then be made in this negative mould. The plaster casts, representing the external features of the original object, are very valuable to have at hand, while engaged in reconstructing the internal features from the wax plates.°

The method of making every fifth ]ilate a black one ha-^ proved to be extremely valuable in arranging the wax jilates. In this way it is easy at any time during the reconstruction of the model to count up and place any given section.

The method of reconstruction which I have found most convenient is as follows: After the "plates are placed in proper jiosition so that the external features of the object are accurately portrayed, I begin by taking oil' five plates from one side. The draAvings of the sections I likewise have pinned together in groups of five in the same order in which the plates are piled. By going over the five finished drawings it is easy to obtain a good conception of the form of the structures represented in the block of five plates under ctmsideration. I have at hand a paper of fine pins and these 1 l)ress down through the various structures seen in section on the surface plate, and in such a direction that they will pass into the same structure in the sections below. When the parts of the plates which represent the structures to l)u reconstructed are thus firmly united by pins I remove the intervening portions of the wax plate with a pair of force] s. Thus, in a very short time, one is enabled to l)ring to light the form of the structures lying within the block of five sections. The pins hold the various bits of wax firmly in place and serve to strengthen the model in every way. When I feel satisfied with the appearance of the structures in the first block of five sections I proceed to the next and treat it in the same way. Those structures which are cut in both liloeks of sections may at the same time be ])inned together. After two or three blocks of sections have thus been piled up it is often well before adding another lilock of five sec


■J Many methods liave been devised of pilini; plates acciirdhiir to special marks. The method devised by Wilson, Zeitschrift fiir wissenshaftliche Miliroscopie, xvii, IDOO, page 17T, seems a good one.


April-Mat-June, 1901.]


JOHNS HOPKINS HOSPITAL BULLETIN.


151


tions to fuse them together with a hot knife and thoroughly to strengthen the reconstruction so far as it is completed. For strengthening piles of narrow strips of wax, representing sections through membranes and the like, a wire netting is of the greatest value. Perhaps the best form of wire netting for general purposes is a copper netting with 10 strands to the centimetre. The copper netting has no tendency to cause subsequent warping, as is the case with iron netting. The netting is heated in the flame of a Bunsen burner and is then applied to the surface which it is desired to strengthen. In case of narrow columns, such, for instance, as are formed in the reconstruction of blood-vessels and nerves, copper wire is of the greatest value. This can be heated and sunk in at one side and then fused over.

After the model is once well started the subsequent building up can proceed with great rapidity. Plates in blocks of five are added as described above until the model is finished. Of course a greater or less number of plates than five may be used to a block. In most of my work, however, I have found blocks of five, with a black plate on the surface of each block, to give the most satisfactory results.

In order to keep the various structures distinct during the reconstruction it is often of value to paint them with dilferent colors, while the work proceeds. The various structures of a model built up as described may be removed as completed, or during the course of reconstruction, and then readily replaced. Pins are of great value in holding structures iri


place and for indicating where a structure removed must be replaced in order to regain its proper position.

If it is desired at any time to cut the model in a given direction the pins which hold the pieces of wax together may be readily cut with scissors.

3. I have mentioned methods by which ihe model is greatly strengthened during the course of reconstruction, the use of ])ins, of wire netting and of wire. All three means may be employed thoroughly to strengthen the mod«l after the first rough reconstruction. The wire screening is then especially valuable. Of course it is possible to add free hand and with a good deal of accuracy structures which from their delicacy are diflicidt to model. This is true of blood-vessels, nerves and of fine membranes. The blood-vessels and nerves may be readily constructed by covering copper wire with wa.x, the membranes by covering a netting of narrow meshes with a thin coating of wax.

In rounding and smoothing up various structures in a model so as to give it a finished appearance, semi-melted wax a])])lied with the fingers or with a spatula is of the greatest help.

Tlie model is greatly protected in many ways by a thick coating of paint. Hot weather seems to have a far less detrimental effect on such models than on models unpainted.

We have found jihotograjdiy of great help not only in recoi'ding the condition of the finished model but also, at times, during the course of a reconstruction.


MODEL OF THE NUCLEUS DENTATUS OF THE CEREBELLUM AND LPS ACCESSORY NUCLEL

By Harry A. Fowler.

(From tJu Aniilomictrl Lahoyaionj of the Johns Hopkins University.)


At the suggestion of Dr. Barker I have undertaken the study of the central gray matter of the cerebellum and its relations to the white fibre bundles to which it is intinuitely related. It has seemed advisable to make a partial report including a reconstruction in wax of the nucleus dentatus and its accessory nuclei.

In a study of the internal structure of the cerebellum it is necessary to consider the work of Stilling on this region. To him belongs the credit of being the firet to study the internal anatomy of the cerebellum by means of serial sections made in various planes and stained with dyes to bring into greater contrast the white matter and the gray masses. With the crude methods at his disposal for preparing serial sections and staining them, the drawings of Stilling show with remarkable accuracy the relations of these central nuclei to the white substance in which they lie buried and to which they are closely related.

The Material. — The model was made from a series of transverse sections through the medulla and cerebellum of a newborn babe prepared by Dr. John Hewetson in the Anatomical Laboratory of the University of Leipzig. The material was hardened in iliiller's fluid, cut ^0/'. thick, and stained bv the


Weigert-Pal method. Every other section was used and hence each section represents a thickness of 110 microns. A series of sagittal sections through the medulla and cerebellum of a new-born babe was also prepared and treated in a similar way for use as a control in measurements and to furnish an outline of the floor of the fourth ventricle. This outline was used in building up the model.

The Method. — Bern's method for nuiking wax jilates as carried out in this laboratory has been fully described by Dr. Florence R. Sabin.' A magnification of twenty diameters was decided upon, because (1) it gives a plate of convenient size to work with so that the numerous foldings of the surface of the dentate nucleus can be distinctly outlined, and (2) the thickness of the jjlates — 2.8 mm. — makes them easy to cut and convenient to liandle — two points of considerable practical value. Outline drawings were nuide first with a projection apparatus at a magnification of twenty diameters. These drawings were then controlled with a higher magnification before transferring them to wax plates.

In building the model a real difficulty presented itself — the


' Sabin, Contributious to the Science of Medicine, and .Jolins Hopkins Hosi)ital Reports, ix.


152


JOHNS HOPKINS HOSPITAL BULLETIN.


[Nos. 131-122-133.


difficulty of controlling the curves. Inasmuch as the central nuclei of the cerebellum lie deeply buried in the wliite matter of the hemispheres and worm one does not have tlie assistance afforded by external form in building up the model. In studying the sections it was noted that the dentate nucleus and accessory nuclei are bisymmetrieal, and a prolongation of the raphe of the medulla dorsalwards Ijisccted the cereIjellum, passing through the middle point in the roof of the fourth ventricle. Corresponding points in the nuclei of the two hemisjiheres were equidistant from the median line so drawn and from the middle point in the floor of the fourth ventricle. In building the model these two guides were used: (1) the median line which controlled the lateral curve, and


to the lowermost (distal) section, in which the dentate nucleus appeared, was placed at a proper distance from the median line, i. e. the edge of the board and the upriglit outline of the floor of the fourtJi, ventricle, and fi.xed in place. The succeeding plates were piled with reference to these two guides and the plates already piled, and each plate as it was put in proper position was fused with the plates already fixed.

The outline of the nucleus dentatus is very definite and easily traced. Tlie capsule or Vleiss (Stilling) on the outside and tlie cor.' or llarkkern on the inside are both medullatcd and take the stain, thus distinctly limiting the yellow mass of cells composing the nucleus. The drawings could be very accurately made. In attempting to outline the accessory



TiXU &.ii\ N\[ai. Nuoa.m.

Fig. 1. — Transverse section of medulla and cerebellum (after Sabin, J. H. H. B., No. 81, December, 1897, Fig. 3.) Section at level of uucleus of glossopliaryngeus and vagus nerves. Section also passes througli upper part of the dentate nucleus and accessory nuclei. Long axis of nucleus is seen to form an acute augle, with the median Hue (formed by extension dorsally of the raphe bisecting the 4th ventricle aud the cerebellum), with the augle openiug toward the medulla. Dorsolateral surface of dentate nucleus is parallel to the surface of cerebellum. Corpus restiforme is seen to cover this surface. The accessory uuclei appear separated and broken up by the white meduUated fibres. Variatious in thickness aud foldings of walls of the dentate uucleus also well shown. Ililus ojiens medial- and ventralwards.


(2) the outline of the floor of the fourth ventricle which controlled the dorsoventral curve. In the sagittal series the section passing through this central point in the floor of the fourth ventricle was selected and an outline of the longitudinal curve of the floor was made. A flat surface having one straight edge was then obtained. This edge corresponded to the median line. To this edge was attached .the outline of the floor of the fourth ventricle, already described, at the proper angle corresponding to the angle at which the sections were cut. With these two guides fixed the plate corresponding


nuclei, however, one meets with a real difficulty. This applies particularly to the nucleus globosus and the nucleus of the roof. The nucleus globosus instead of forming one mass of gray matter is made up of several irregular groups of cells separated by deeply stained meduUated fibres belonging to the fibre systems of this region. These separate groups arc clearly limited with a magnification of twenty diameters, but when studied under higher powers one finds cells evidently belonging to these groups scattered among the dense network of deeply stained fibres. In studying the nucleus globosus


Apbil-Mat-June, 1901.]


JOHNS HOPKINS HOSPITAL BULLETIN.


153


through several consecutive sections under high jjowers one gets the impression tiiat the separate groups seen with a magnification of twenty diameters really form one nucleus; that this lai'ge mass of cells is separated into groups by the white fibres plunging directly through the nucleus; and this impression is further strengthened by noting the cells scattered among the fibres, included as it were by the bands of white fibres.

In outlining the nucleus of the roof one meets \\itli the same difficulty. In going over these two nuclei with a high power to correct the drawings for transference to wax I had to include the scattered cells referred to. I did this by making the nuclei solid, not attempting to indicate the space occupied by the fibres.

One other point is to be noted. The so-called accessory nuclei, i. e. N. emboliformis, N. globosus and nucleus of the roof, are usually described and figiired as entirely separate and distinct cell-mass. In this series of sections of the newborn babe, with the exception of the N. emboliformis, it has been difficult, indeed impossible, at certain levels, to separate these nuclei. The N. emboliformis forms a perfectly definite cell-group, in the lower (distal) sections, appearing as a thin, tongue-like ribbon of cells almost entirely occluding the liilus of the corpus dentatum. Sections at the level of the middle of the nucleus show it changing its shape, suddenly becoming thicker and shorter, but clearly separated from the corpus dentatum on one side and the nucleus globosus on the other side by thin, deeply stained bands of white fibres. The nucleus globosus also appears as a definitely limited and separate group of cells in the lower (distal) sections, appearing in sections a little above the beginning of the hilus of the corpus dentatum as a small oval area of gray matter. At a higher (proximal) level this oval mass is divided, as already indicated. At the highest levels it is not to be separated from the nucleus of the roof.

Corpus Dentatum. — It is embedded in the cerebellar hemisphere "like a peach stone" (Stilling). The distal end lies more deeply buried in the white substance; the proximal end approaches closely to the roof of the fourth ventricle, from which it is separated by a thin ribbon of white siibstance. Horizontal sections of the nucleus, as pointed out by Obersteiner, do not show the greatest diameter of the nucleus. This appears in sagittal sections.

The dimensions of the model of dentate nucleus are as follows:

1. Proximo-distal (sagittal), ID.Scin.

3. Mesolateral, (iu axis of nucleus ami nut at riglit angles to median line), 19.4 cm.

.3. Dorsolateral, (perpendicular to mesolateral axis), 7.8 cm.

Remembering that the longest mesolateral diameter forms an acute angle with the median line with the angle opening ventralwards one will understand the measurements given.

The nucleus dentatus is really a hollow shell or sac with its long axis directed antero-posteriorly (proximo-distally). This shell is flattened dorsoventrally or at right angles to its mesolateral diameter. The walls, which vary in thickness


from 0.3 to 0.5 mm., are thrown into numerous folds also varying in number and size in different parts of the nucleus. The folding of the walls gives to the svirface an appearance not unlike the surface of the cerebral hemispheres or to the gyri and sulci of the inferior olive. The shell of gray matter is not closed but freely opens above (proximally), while the ventral and mesial walls are incomplete in the anterior (proximal) two-thirds of the nucleus. This opening in the walls forming the so-called hilus — hilus corporis dentati — looks median-, ventral- and cerebralwards. In the distal one-third of the nucleus the walls are complete and in transverse sections appear as oval closed rings or ring of gray matter.

The hilus in the more distal sections opens directly medianwards; in sections at a higher level (cerebralwards) the opening increases rapidly in size, the ventral wall becoming less complete, while the dorsal wall forms a complete covering. As a result of this progressive shortening of the ventromesial wall the hilus comes to open wider and wider ventralwards. This direction is further emphasized by the relation of the nucleus emboliformis. In the most distal sections lying within the mouth of the hilus it is in very close relation with the dorsolateral border, indeed in the distal sections it may be considered as a continuation of the dorsolateral surface on to the mesial surface, being separated by a very thin band of white fibres. This relation continues throughout the entire length of the nucleus, there being only a thin space of separation through which pass the most dorsal fibres escaping from the Markkern of the nucleus dentatus.

In addition, the dentate nucleus presents for description two surfaces, (1) dorsolateral, and (3) ventromesial; and four borders, (1) mesial, (2) lateral, (3) proximal, and (4) distal.

Dorsolateral Surface, — This is the largest surface of the nucleus (Fig. 2). It is irregularly quadrilateral in shape and lies parallel to the surface of the cerebellar hemisphere. The lateral and antero-posterior (proximo-distal) curves are slight, the surface being quite flat. In this connection it is interesting to note that a portion of the corpus restiforme lies over this surface of the nucleus, forming a shell enclosing the dorsolateral surface. This surface terminates mesially by a sharp thin border in its upper (proximal) two-thirds, by a rounded mesial border in its lower (distal) one-third. Laterally it is limited by the thicker, irregular and rounded lateral" border. The proximal border also thin forms with the median line an obtuse angle opening spinalwards. The distal border is parallel to the proximal, is thick, rounded and is broken into by deep sulci. By reference to Fig. 2 it will be seen that the lowest sections of the nucleus includes only the mesial- portion of this border.

The dorsolateral surface is traversed by five parallel deep fissures, which run parallel to the long axis of the nucleus. Beginning with median line these may be designated as A, B, C, D and E. These fissures divide the surface into six columns or gyri. Besides these five primary fissures there are five secondary sulci, which are shallower and incompletely divide the primary columns or gyri into secondary gyri. By reference to Fig. 2 the following jioints will be noted: Fissure


154


JOHNS HOPKINS HOSPITAL BULLETIN.


[Nos. 131-122-133.


A is parallel to the mesial border, it is relatively deep and its corresponding gyrus on the inner surface of the nnelens looks lateralward (Fig. 3). The proximal end of fissure A curves laterall)'. Fissures B and C present three curves, the pro.ximal and distal with convexities pointing mesially, the middle vi'ith convexity laterally. Fissure C is incomplete, its proximal end not reaching the proximal border. Fissures D and E form acute angles with fissure C with their proximal ends pointing obliquely medialwards. It will also be noted that the distal extremities of the columns or gyri are larger, thicker and divided by extension on to this surface of the fissures from the ventromesial surface. The deep fissures of the ventromesial surface alternate with the fissures on the dorsolateral surface. An exce])tion to this is in fissure D, which is really an extension on to the dorsolateral surface of the lateral fissure of the ventromesial surface. There is no evidence of distinct lol)ulation visible on this surface.

The secondary sulci are limited chiefly to the three gyri nearest the median line. In other words, the folding of the dorsal wall of the nucleus is greatest nearer the mesial and proximal borders; it is thickest nearer tlie lateral and distal borders.

Ventrolateral Surface. — This surface is incomplete in its upper two-thirds. It difi'ers markedly from the dorsolateral surface. It presents two deep fissures radiating from a point near the hilus about the level of the middle point of the nucleus. These fissures may be designated as (1) internal and (2) lateral. AVithin the internal fissure and nearly covered over by its projecting edges is a gyrus, broad at its base (distal end) and tapering above, becoming lost in the most proximal part- of the fissure. This gyrus, partly concealed within the internal fissure, divides thi^ fissure into two, both of which extend so as to appear on the dorsolateral surface. These two fissures, internal and lateral, of the ventromesial surface, divide this surface into three lobes, (1) internal, (3) median, and (3) lateral. The internal is the smallest and continues below the hilus on to the mesial border, being distinctly marked off from this border by a shallow s\ilcus. This lobe is broad at its proximal end, tapering off distally. The median lobe, broad at its base — distal end — narrows toward the point of divergence of the two fissures, internal and lateral. The internal and median lobes form the most distal part of the nucleus as viewed from its ventral aspect. They slope with a considerable curve to meet the almost perpendicular dorsolateral surface. They present no secondary sulci.

The lateral lobe is the largest. It forms the lateral border and extends on to both dorsolateral and ventromesial surfaces. On the former it lies lateral to fissure L\ while on the latter it is limited mesially by the lateral fissure. This lobe is most irregular in outline, is broken up by numerous depressions and several secondary sulci. One of these sulci, more conspicuous than the others, runs parallel to the upper two-thirds of the lateral border.

The upper two-thirds of the ventromesial border is incomplete; the margin is very irregular as will Ijost be understood


by reference to Fig. 3. In general, it may be said that this surface, as compared with the dorsolateral, presents (1) deeper fissures, which give the appearance of lobulation, (3) thicker walls, and (3) fewer foldings of the walls.

The proximal end of the nucleus being open this border is limited to the thin edge of the dorsolateral surface, and the very small part of the ventromesial surface. This border slants obliquely spinal- and medianwards. The other borders have been referred to in describing the surfaces and the hilus.

llie Accessory Nuclei. — The form and outline of the accessory nuclei, i. e. the nucleus emboliformis, nucleus globosus and nucleus of the roof, have been already referred to. Figs. 5, and 7 show these nuclei in relation to the dentate nucleus. In Figs. V, and 7 the nucleus embnlifurmis is seen as a long thin sheet of gray matter separated from the dorsolateral surface of the nucleus dentatus by a narrow space already described. Its most distal end nearly occludes the hilus corporis dentati (I'ig. 7), while proximally it changes its form, becoming thicker and shorter, encroaching less on the hilus. It will also Ije noted (Fig. 5) that its axis changes; at first running dorsoventrally in its distal extremity, it comes to lie more latei'ally in its proximal ]iart. corresponding in direction with the dorsolateral wall of the dentate nucleus. This nucleus is practically sc])arate throughout its entire length, being the most definitely outlined of the accessory nuclei.

The nucleus globosus (Fig. 5) is also seen as a distinct oval mass of gray matter in its distal ]iortion, beginning a little above the appearance of the hilus. In its proximal end this nucleus is represented as fused willi the nucleus of the roof (I'igs. 5 and 1).

The nucleus of the roof appears in the reconstruction as a large irregular mass, distinct in its distal portion, becoming fused with the nucleus globosus in its proxinuil portion. The outlines of this nucleus are indefinite in this series, its ventral surface being in very close relation with the gray matter of the roof of the fourth ventricle.

DESCRIPTION OF PLATES XXIX-XXX.

Fig. 2. — View of dorsolateral surface of model of N. dentatus. Proximal end corresponds to top of figure; median line is to left. J/, mesial border; T, lateral border; ,1, B, C, J), Ji, are placed over primary fissures; n, b, i; d, e, over secondary sulci; /, is extension on to dorsolateral surface of tUe internal fissure of the ventromesial surface.

Fio. 3. — View of ventromesial surface of model of N. dentatus. Median line to rii;lit. 7, internal fissure ; L, lateral fissure ; i, internal lobe; i/i, median lobe; I, lateral lobe; H, bilus.

Fig. 4. — View of mesial border of same at right angles to median line. Relations of hilus to dorsolateral and ventromesial walls are shown. Distally the hilus is narrow, increasin;;- rapidly as one passes cerebralwards.

Fig. .5. — View of mesial border of N. dentatus with accessory nuclei in place.

S, nucleus emboliformis; O, nucleus globosus; S, nucleus of the roof; o, narrow space through which escapes UK^st dorsal fibres from MarkUern.

Fig. 6. — View of dorsolateral surface of same. Legend as in Figs. 3 and .5.

Fig. " View of ventromesial surface of same. Legend as in Figs.

3 ami 5.


THE JOHNS HOPKINS HOSPITAL BULLETIN. APRIL-MAY-JUNE. 1901.


PLATE XXIX.



Fig. 3.



Fig. 3.


Fig. 4.


THE JOHNS HOPKINS HOSPITAL BULLETIN. APRIL-MAY-JUNE, 1901.


PLATE XXX.



Fig. a.


Fig. 6.



Fig. 7.


Ai>i!il-May-Juxe, 1901.


JOHNS HOPKINS HOSPITAL BULLETIN.


155


USK OF THE 3IATKIUAL OF TIIF DISSECTIXd ROOM FOI! SCIENTIFIC ITRFOSES.

By C.'iiAJti.ES i;i>--^i:i.i. Bardeen, M. D., A.ssoi'idh' ill Analiiiitij. J</liii^ IloiiIiHis I ' iii rrrsili/.


L'liseiiln'i'g. in ;i ruL-eiit iirticlr.' Ii;is failed atli'iitioii to ihe oj]|i(irtunitic>.s that the disseeting room offers I'or seientilic investiuation. He gives an interesting siunniarv of the various atteni]its that have been made to take advantage' of tlv s.' ojiportnnities. and calls |iartieular attention to the records obtained by Selnvalbe at Strassburg. by C'nuningham at Dublin, and bv tlie Anntonncal Society of (ireat l'>ritaiii and Ireland.



Fig. I.

It has seemed In me that the mctlinds employed In utilize the material of the dissecting room ami the work of the students for scientific purjioses in Professor MalTs lab(jratory at the Johns Ilojikins TTniversity, iialtimore, uuiy ])rove ol' interest, ]iossibly id' value, to those engaged rl.-c\vliere in anatomical instruction.

The immense amount of study that luis been given to thi' structure (d' the human b<idy during the last foui- ci'uturies reiulers it nnli]<ely that tlu' stiulent's initrained eye and hand could be utilized to advantage in a search for unrecorde 1


' Mi>r|'li(iluu:isr'lK's .Talnhiich, isii.i


facts of gross structure even if tinu' [lermitted him to delve in those little nooks and corners where the records are still incomjilete. The very considerable amount of variation, howevei'. which the individual liodies present in the structure, form and relatioiislii])s <>( their various organs, olfeis a rich field for cxdtivation.

Since tlie time of ])arwiu much attention has been given to the study of variations in plants and animals. The greater part of the attenticn. however, has been given to external features, to variation in size, color, and e-xternal fmni. Few studies have Ijcen made of the frequency of variation in the internal organs. Yet ]irobably the body of no animal is more suited to this study than that of man and none is studied with care by so great a number of indi\iduals each year.

Until couiparali\ely recently the variations brought to light by the dissector have lieen recorded only when of an unusual nature. These observations, however, have been so numerous that we may assume that most of the variations likely to be brought to light have previously been recorded. While the limits of variation of the various organs of the liody are thus fairly well understood, the fre(|ueucv of variations has Ijeen determined but for few organs and for them only incom]iletely. The true "'normal'" or "most usual" is unkniiwn. lleiile. in his anatomy, pictured tlud as nnriual which his experience led him to think the most usual. Most of the other leading anatomists have done likewise. No two books, otlier than comjulations from siuular scuii-ces, give the same account of the normal form of the various organs. The great ojijiortunity whicli the dissecting room olfers is that of determining the curve of frequency of the various {'(u-ms presented by bodily structures, and thus to make the normal a question of measurement rather than one of jiidguumt. To render this jjossible. accni-ate records of the ccinditions found in each body must be uuide. of such a nature that they may be afterwards compared and reduced to tables.

The method u( rec(U-d thus becomes a question of paramount importance.

In the Anatomical I/aljoratory at the Johns Hopkins Hniversity the first attemjits at making systematic records of conditions of structure revealed at the dissecting table were begun in tlu' fall <d' IS'i:.. It was determined to make a study (d' the variatiiuis in the <list ributioii of tlie ei'auial and s]iiiial nerves, especial attention lieiiig paid to the cervicoiu-achial and the lumbosacral plexuses. .\l the instigation of Professor JIall, Dr. .V. W. h'lting. at that time Assistant in Anatomy, prepared three record-charts, one for tiie nerves of the head, one for the nerves of the neck, arm and upper half of the thorax, and one feir the lower half id' the body. On these charts a iceord v\'as made (d' the sex. color, and aiie


as well as of the nerve distrilmtion in the body of tlie individual dissected. The seheme for recording the latter was as follows. On separate .successive lines the numerical designation of a given cranial oi- spinal nerve was placed, followed hy a list of the names of tlie nerves (o which the given main nerve li'unk was assumed to conti'ihnte. In the preparation of this table the standai'd anatomies were consulted. A few


The student.s were requested to compare carefully the nerves in the part dissected witli tlu' outline scheme, to unileiliuc Ihe names of those nerves wliich were found to coi'rcspond willi the sclu'me. to cross out the names of the nerves whicli did not thus correspond, and to insert these names in llic prii|iei- place. Complex conditions, such for instance as ai'c fmind in the cervicohrachial and the lundjo


Fui.


lines from the " ( 'cr\ico1ii-acliial Chart" may sulllce to make clear the general nature of this scheme:

C. VI. I'oST-liU. AnT-BU. _roST-TI10UAClC. SUISCI.AVIUS. SUPiiA scAP. Com. C. VII.

C VII- PosT-Bit. AsT-uit. — Extant TiioKAcic. Com-post. coud. Outer Cord. Musc-cut. — Vor-brai-h. Biecps. hr-ant. Ant. Post. OuTEii-ilEAP-MEDiAN. — Aiit-inUros. raliii-cut. Tliinnb-hr. .5 DiijitaU.

C. VIII. PosT-nu. AxT-mt. Inner Cord. Post. Cord. Sii!SCAPS. — Upjjir. Middle. Lcwrr. CiiicuiiFLES.. — Siip. Inf. Art. Muse. Spiral. — Musi: Int-eut. Ert-np-ciit-hr. A'.rt-lou<-cut-bi: Mnsc. Radial. — Exl-bi: Inl-bi-.t. 4. PoST-lNTEiios. — .l/"sr. .1/7. CoJi. 1). I.


saci'al plexuses, woe illustraled liy diagrams drawn on the backs of the charts.

These outline schemes were well arranged and Ihem'elically should have workeil well, '^'ei they did not prove a success in the hands of the students. The suggestion induced by print seemed continually to lead the student into reading the scheme into his "]>art." The task of verifying the charts thns became a severe one. Another diltlculty came from the fact tluit names can mean little so long as the '■ mirmal " is unknown. While the larger nerves arc so constant in position that the names cin'reut in the text-books


Ai'1!1l-May-June, 1901.


JOHNS HOPKINS HOSPITAL BULLETIN.


157


could be used without confusion it was I'diiud that many of the smaller nerves could he definitely rcennlcil nniy l)y attachiufj a sjieeial definition to the name, 'i'lic iliohi/iiof/aalric and the ijcnUocrural nerves may lie iiiciil inncd as examples. The value of these earlier charts lies rather in tlie ilhistrative diagrams of the plexuses placed on llie liaiks of the charts than ill the records made on the tabulation seiiemes.

Ill the fall of 1897 I undertook the iiniiiediaie sii|iervisiiin of these records. I discarded In a coiisidiTablc cxlcnt the use (if thi- ]iriiited schemes. The students were ciicouraLjed to record the distribution of the nerves by making free-hand


of tlie front of liie thigh; one for the sacral plexus; one for the })erineuiii; one for tlie back of the thigh, etc., in all 36 charts.'. Separate charts are used for the riglit and left sides (if the hoily.

In these diagrams tlie bdiu'S and the surface (lullinr of the body after the remciva] (if the skin and tlie superHcial fascia are indiealed by hue Hues |ii-inled in brown iii1<. The scale of the charts varies I'l-diii niir-balf to full bl'e size, according to the I'egioii to bi' charted. In this way the general average jirojiorf ions of tlie vari(nis parts of tlie body are furnished the student. JMarked variations from these proportions can



Fic.


diagrammatic sketclies to illustrate the cdndilinns found in the parts dissected. "Many of thi' drawings ihii,~ made were well executed. Yet few of the stmh'Uts are snnicieidiy skillful draughtsmen to make even these simple sketches without a, great expenditure of time. I therefore devised a si't ol' simple outline diagrams on which the nerve distribution can lie recorded. These diagrams are arranged for llu! various parts of the body. Thus there is one for tlir alHldiin'ii, which can hi> used cither for the nerves of the alMldiniiial walls cr for the liiiiihai' plexus (see Figs. 1-3); anotbci' fcir the nerves


readily be imlicaliil by changing the faint outlines of the skeletal scheme. .Vflci' removing the skin from a given part of the body the stiiclcnl draws on the appropriate diagram the course (if the superficial nerves as lie finds them running in the fas<'ia. When the muscles have been dissected out the ner\i.' supply of the various muscles is charted. Muscles and other slructures are drawn in to show the g<'neral relations of

- ■flii'si- cliiii-ts liMvr lirrn |.n li I i sliL'd ill iniiiiplili-t fonii; •' Oiitliiii'. lli'cnra Charts." ■flii.' J.iiins lloiikins Press, Baltimore, IHUO.


llic iKTvef!. The best ix-fovd.s have been obtaiiicrl when the student luis attempted to record only a few siiiipli' iimditidns nil a sinnh' chart. Tims in cliartini;- the nerves id' llir rnnil uT the tlii.^Ii separate eliarts are used to record the ihslrilui


J./" MS/,„


Fig. 4.

tioii io tile siiiii)rliis rnusck^, to tlie redii-^ muscle, to tlie dei'p c.i:teiisur muscles, to the adductur lo)i(jii.s muscle and the (jranlis. to the adductor lirevis muscle, and lo llu' addndur iiiiiijims and rxleninl ohlurator muscles.

To illustrate the method of using these charts a few ex


amples may be aiven. I'^ip. 1 I'cpresents the outline diafrram used For the alMhuiicii and the lumbar region. Fip. 2 shows the distribution oi the main ventral trunks of the abdinninnl nerves as dissected out and recorded by two students, fiu. 3 represents the lumbar plexuses and the distribution of the ' Ijorder nerves" found in the same subject. The lateral branches of the abdoininal nerves are shown in auntlu'r chai't (Fig. 4).

Of course one cannol hope to get from students the com])lete and accurate records which one could get by }iersonal di.ssection. It is cnily rarely that perfectly satisfactory records are ol)taiiied of (he [leripheral distribution of all the nei'ves. On the other hand, it would be a physical impossibility by personal dissection to get the same number of records in the same si)ace of time. Mistakes are more likely to be those of omission than of a jiositive nature. The student may destroy some fine nerve twig before it has been seen by an instructor, and thus it may csca])e record. The conditions that the average student finds and records are, however, of great value. Thus only may we ho])e to get that large number of records frcun whiih a curve of frciiucncy may be detei'inined.

In aihlition to the oi.tline diagrams I have devised a simple printed scheme for keeping record of the race, sex, age, size, skeletal peculiarities and marked variations from the normal in the various organs of the body. This latter set of records is made out Ijy the instructor who verifies the charts.

The verification cjf (he charts is one of the most important features of the undertaking. Without careful verification by one man who gives his time in the dissecting romn mainly, if not wholly, to this task the charts can be of little value.

Active co-operation on the part of all the instructors and of the students in the dissecting room is also essential.

The conditions which at iircsent prevail in our nu^dical department render it also perhaps more than usually easy to get the co-operation of the students in carrying out work of this kind. The standards of admission to this school bring us a much nuu-e highly trained class of students than thos.' usually found entering the average American medical schocd. On the other hand, the routine of a graded com-se, while inferior as a method of education to that freedom of choice which nuirks the German university, renders it much easier to win the co-operation of the students in this work. The number of students dissecting each year since the beginning of the undertaking has averaged about one hundred.


Cite this page: Hill, M.A. (2020, April 3) Embryology Paper - On the origin of the lymphatics in the liver (1901). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_On_the_origin_of_the_lymphatics_in_the_liver_(1901)

What Links Here?
© Dr Mark Hill 2020, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G