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| =Note on the presence of the fifth aortic arch in a 6 mm pig embryo= | | =Note on the Presence of the Fifth Aortic Arch in a 6 mm Pig Embryo= |
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| Edwin E. Reinke | | Edwin E. Reinke |
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| ==Bibliography== | | ==Bibliography== |
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| Coulter^ C. B. 1009 The early development of the aortic arches of the cat, with especial reference to the presence of a fifth arch. Anat. Rec.,voI. 3, no. 11. | | Coulter C. B. 1009 The early development of the aortic arches of the cat, with especial reference to the presence of a fifth arch. Anat. Rec.,voI. 3, no. 11. |
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| Evans, H. N. 1909 On the development of the aortae, cardinal and umbilical veins and other blood vessels of vertebrate embryos from capillaries. Anat. Rec, vol. 3, no. 9. | | Evans, H. N. 1909 On the development of the aortae, cardinal and umbilical veins and other blood vessels of vertebrate embryos from capillaries. Anat. Rec, vol. 3, no. 9. |
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| ==THE WISTAR INSTITUTE, DEPARTMENT OF EMBRYOLOGY==
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| At a conference of ten anatomists held at The Wistar Institute, on April 11, 1905, it was recommended that the principal object of the Institute be research, and that the work shall be in the fields of neurology and embryology. This action was approved by the Board of Managers a week later and was incorporated in a letter by General Wistar to these scientists, inviting them to become members of a permanent Advisory Board of Anatomists of The Wistar Institute (see Bulletin No. 1 of The WLstar Institute of Anatomy and Biology, September, 1905).
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| The Advisory Board considered it best to proceed with the organization of the department of neurology first, and accordingly Professor Donaldson of Chicago was elected head of this department. With him were associated Dr. Streeter and Dr. Senior, both of whom were subsequently called to chairs of anatomy in important universities. The work of the department of neurology is now well established, as outlined in Bulletin No. 1, and by Dr. Greenman in the Anatomical Record of June, 1907.
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| In the meantime, funds have accumulated which enable the Institute to support properly a department of embryology, and at the meeting of the Advisory Board held on April 25, 1910, Professor Huber of the University of Michigan was nominated for this office. Prof. Huber has been secretary of the medical faculty of the University of Michigan since 1897 and director of the laboratory of histology and embryology since 1898. In 1901 he was elected secretary of the American Association of Anatomists, and he has been an editor of the American Journal of Anatomy and of the Anatomical Record since their foundation.
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| Dr. Huber will reside at the Institute from March to September in 1911 and 1912, after which it is hoped that he may devote his entire energies to the work of the Institute. It may be recalled that the appointment of Dr. Donaldson was made under like conditions.
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| It is not possible at this time to make any definite statement regarding the work of the new department of embryology, but it is the purpose to make it largely a place for the study of human embryology and its relation to anatomy in general. It will be necessary to make collections of human and other mammalian embryos, especially early stages, for study at the Institute as well as for investigators elsewhere.
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| Cooperative investigations and conferences of specialists similar to those of the Brain Commission are even more needed in the study of human development than in neurology on account of the nature of the subject. It is hoped that the Institute will become a central station through which information may be obtained concerning collections of human embryos and to assist individual investigators to secure, by exchange or through loans, the necessary specimens. However, the chief work of the new department will be at the Institute, but it will assist others and cooperate with them in every possible way.
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| A SIMPLE DISSECTING TABLE
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| H. R. WAHL
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| The dissecting table illustrated above was designed for use in the Anatomical Laboratory at the University of Wisconsin. It consists of a frame-work made of ordinary one-inch iron piping and of a movable galvanized iron top. The legs of the table are braced by iron piping placed six to eight inches from the floor. These braces not only strengthen the table but also provide a convenient foot-rest for the student while dissecting. The great advantage of arranging the piping as illustratedlies in the fact that no obstacles are offered to the knees of the student while sitting on the stool during dissection. The galvanized iron top is six and one-half feet long, two feet wide, and when placed on the frame is three feet above the floor. It is grooved in such a way that the sides slope gently towards an opening in the center. Below the opening in the center a rack is suspended for holding the drainage jar. The table is inexpensive and can readily be built by any plumber or steamfitter.
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| A CRITICISM OF OUR MODERN TEXT-BOOK OF
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| ANATOMY
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| ROBERT RETZER
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| The University of Minnesota, Minneapolis
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| It may be claimed that the criticism the writer is about to make applies more to the previous training of the medical student in high schools and college than it does to the text-book of anatomy, but even admitting that it does, there is no reason why the authors of text-books should not consider the conditions as they are. It seems to make but little difference whether the student is a college graduate or whether he has had but two years of college training, the fact remains that he does not know the meaning of most of the names in the anatomical terminology. It is no exaggeration to say that even such simple words as tuber, sartorius, buccinator and even caput, do not convey anything to the student. Latin and Greek are taught as methods in the high school and college and little stress is laid upon the importance of the vocabulary that the student of these subjects should naturally acquire. It is evident that he forgets the vocabulary in order to leave his mind more receptive for such subjects as mathematics, chemistry and biology. It is deplorable that most students who intend to study medicine do not learn enough Greek to be able to at least read the Greek characters. However, it is not within the scope of these remarks to suggest reforms in the early training of our students; it is the writer's intention to merely call attention to the status quo, and point out where our present text-books fail to attempt to- remedy the evil caused by the early training of the medical student.
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| Four hundred years ago. Jacobus Sylvius, following the example set by Galen, gave names to most of the muscles of the human body. In doing so he considered their origin (brachialis), their structure, (biceps, membranosus), their shape (serratus), and their size (magnus, brevis). Previous to his time numerals were applied. It goes without saying that it made the memorizing of anatomical terminology considerably easier. That Sylvius should have used Latin and Greek words is evident. Latin was the language of the learned, and all scientific treatises were written in Latin. From Hippocrates he took the Greek words. In those days every student understood the meaning of the terms and it is unlikely that any should have made the mistake of calling the serratus anterior
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| 464 ROBERT RETZBR
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| muscle the latissimus dorsi, as some of our students do to-day. Yet most students would resent the inference that they do not know the meaning of the term latissimus.
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| What is the condition of affairs to-day? It has been the writer's habit frequently to ask the student the meaning of the terms thyreoid, ilium, azygos, etc., and of prefixes, mesa, meta, supra, semi, etc. The ignorance displayed by the student was sometimes amazing and one wonders how it was possible for him to graduate from high school, let alone college. Ask a student of average ability to demonstrate the extensors of the wrist and fingers. He wiU probably do so in the following order : extensor carpi radialis longus, ext. carp. rad. brevis, extensor digitorum commimis, ext. digiti quinti proprius, ext. capri ulnaris. Make him b^in his demonstration on the ulnar side and see the result. It has the same effect as asking a person to say the alphabet backwards. This means nothing else but that the student has memorized the muscles in a certain order, and he would be far better pleased if, instead of having long Latin names attached, the muscles were known as muscles I, II, III, etc. Now in the cases cited there is no name which ought to leave any doubt in the student's mind as regards its meaning, and a demonstration ought to be very simple provided the muscles have been dissected out from their origins to their insertions. The student, however, has so accustomed himself to take most of the names found in the anatomic^ terminology as so many meaningless words, that he even ignores the meaning of those which have been anglicized and are us^ by the layman. Thus the term fascia is defined by the student, and imfortunately by a nimiber of anatomists, as a layer of areolar connective tissue. The derivation from the Latin fascia meaning band or bandage is entirely lost sight of, although it gives us the true meaning of the term. Pertioneimi is another instance. Let the student know the derivation, which means to stretch aroimd, and he will not get absurd notions of its being thrown into folds without the intervention of some organ or other structure. Let the student adhere to the idea of "stretching" and many wrong impressions will be dispelled. The derivation of the term oesophagus explains its function, of parotid its position, of thyreoid its shape, etc.
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| The result of this ignorance about the derivation of words is farreaching. In the clinics the same student may characterize a condition whose name ends in '^itis" as a swelling, and the meaning of such important prefixes as haemo, rhino, ileo are absolutely lost to him. He must learn the name of every disease just as he would the name of so many persons. It never occurs to him that about 90 per cent of all the names are descriptive of the disease. Even if most of the blame of this condition is to be laid on the high school and college, there is no valid reason why we anatomists should not begin with a training that is of such vital importance. We have other duties in the dissecting room besides the teaching of anatomy, such as training the student's power of observation, his self-control, his tactile sense, and trying to inculcate a critical or scientific attitude. In a word, we strive to make the student fit to enter upon the study of medicine. It seems but a small additional
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| CRITICISM OF OUR MODERN TEXTBOOK OF ANATOMY 465
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| duty to make the student realize the importance of word-derivation. To make this the subject of a lecture-course is not feasible with the present crowded schedule in our medical schools. It is sufficient for the instructor to repeatedly call attention to derivations, provided the student can find a reliable source of information. What would be simpler than to have this information incorporated into our text-books. It was done in some of our older text-books. The ommission is probably due to the publisher who is instilled with fear at the very sight of a Greek letter.
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| The conditions in Germany are far different. It is attributable partly to the better elementary training in the classic languages and partly to the custom prevailing among the authors on anatomical subjects to use German instead of Latin names. There is no reason why we should not follow the example of our German confreres in at least the latter respect. Why not speak of the tailor muscle, the straight abdominal muscle, the two-headed muscle, the calf-muscle, the medial skin nerve of the fore-arm? It is evident that it cannot be carried through as consistently as is possible in German, because we have but comparatively few Anglo Saxon roots to build upon. Yet the interspersing of a few of such terms will take away a great deal of the oppressing formality of the present text-book and make it far more pleasant reading matter for the students. If any one should doubt that Anatomy can be made the subject of most delightful literature he ought to read the text-book of Hyrtl.
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| The diadactic importance of these suggestions cannot be over estimated. The student will lose that antagonistic attitude toward the subject of anatomy because this attitude is only bred in ignorance. To the average American student of Anatomy at first, especisdly if he begins with a lecture course in osteology, means merely the memorizing of numerous names. The instructor speaks an imfamiliar language,. With the aid of our next text book let the student's attention be called to common prefixes and suffizes, and the derivation of terms. His horizon will be widened immediately, he will use the terms with greater assurance and familiarity and incidentally learn something of the history of anatomy.
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| Fio. 1 The anatomical institute in Munich, over the dissecting room.
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| Histology is taught in the dome
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| BOOK REVIEW
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| Die Neue Anatomische Anstalt in Munchen. Von Dr. J. Ruckert. 109 Seiten und 18 Tafeln. Wiesbaden: J. F. Bergmann. 1910.
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| Professor Riickert's account of the new anatomical laboratory in Munich is of interest to Americans because it will be of great value to those who have similar buildings to plan. We are now in the midst of a development of medical schools which calls for the construction of first-class laboratories by our leading universities. Those who have this task before them will welcome good literature upon laboratory construction.
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| The first anatomical laboratory built at Munich was planned by DoUinger in 1824. (It may be stated that the anatomical laboratory at Johns Hopkins University is in many respects a reproduction of DoUinger 's laboratory.) Soon this laboratory proved to be inadequate, and in 1855 it was rebuilt by Bischoff who made it about as large as the present beautiful laboratory of the Harvard Medical School. Now there is a third stage in the development of medical education in Munich which has called for this "palace/* as the proper home for anatomy in
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| a large and great university. This new anatomical institute is an irregularnahaped building, four stories high, and covers an area of about 200 by 300 feet. Like the Harvard laboratory, which is by all odds our best example, it is a magnificent structure perfect in every respect for the work which is to be done within its walls. However, there are marked differences in the methods and teaching in these two laboratories, which makes Riickert's report especially valuable for the solution of problems of anatomical teaching soon to be encountered by our larger medical schools.
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| During the past academic year about 2000 students received instruction in anatomy in the Munich laboratory. The main courses given were as follows: Practical anatomy, 900 students; lectures on gross anatomy, 600; lectures on art anatomy, 600; lectures on histology and embryology, 500; exercises in histology, 300; and histological technique, 200. There were also nmnerous smaller and informiJ courses given. Since they believe in Munich that the larger a medical school is the better it should be, they have constructed a building in which both large-class instructions and individual instruction are given. One is impressed with what perfection they have met the difficulty of managing large groups, the equipment, machinery and service at the professors' disposal being the best in every respect. The building is immaculate, hygienic and aesthetic, with an ample budget for maintenance and for scientific work.^ Those who have visited the laboratory are greatly impressed and leave with a feeling that Professors Riickert and Mollier have solved their problem in a most satisfactory way.
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| The report is detailed and is not only a good morphological but also a physiological description of the building. It is also educational. For these reasons it will be of use to all teachers of anatomy. All subdepartments of anatomy are well represented. The equipment for the preparation of all kinds of anatomical specimens, sections of embryos, museum specimens^ skeletons, drawings, photographs, X-rays, experi ^ The following figures were obtained from Professor Mollier:
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| The building cost nearly $500,000
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| During the year 1909-10 the budget was. not including salaries 27,000
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| General service, business manager, porter, technician, mechanic, stoker,
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| etc $2,200
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| Heat, light, etc 7,600
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| Library 300
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| Assistants —
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| Gross Anatomy (8) 4,700
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| Histology (5) 2,300
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| For materials, instruments, chemicals, artists, modelers, printing, photography, laundry, scientific apparatus, etc.
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| Gross Anatomy 7,200
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| Histology 2,700
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| Total $27,000
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| mental anatomy, etc., is at hand. There is an excellent collection for teaching and a beautiful display of specimens and models for the general public. As is well known, art anatomy is well cultivated and many students of art receive instructions here. In general one wing is devoted to the beautiful entrance and the reception of the students, the other wing to the staff and research, and the center of the building to the teaching of large classes (see figs. 1 and 2). In the sub-basement there are all sorts of cellars, coal bins, boilers, apparatus for ventilation. Above, in the basement there is the public museimi, cold-storage rooms for cadavers and for the teaching collection, machine shops, and six residences for servants. The first main floor includes in the center the main lecture room and the large dissecting room built in the shape of a clover leaf. In one wing there are cloak rooms, dressing rooms for both men and women, etc., and in the other, rooms for the staff in gross anatomy. The dissecting room and the lecture hall extend upward through the second main floor, which contains also many rooms for the staff in histology and embryology. The large teaching room for histology is in the dome of the building over the dissecting room on the third main floor. Here there are also a very large demonstration room for histology, dark rooms, photographic roomJs, X-ray rooms, etc. Everything is centralized as the main method of teaching is by means of lectures and demonstrations.
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| The bulk of students are passive; they listen to lectures and they witness demonstrations. Only the better students and members of the staff are active, study nature and are self-instructed, as Dollinger and von Baer would have it, and as is only possible for all students in a small laboratory. Both active and passive methods of teaching anatomy are used upon the same students only in exceptional cases. All in all, they have met the diflScult problem of teaching large groups of students exceptionally well in Munich and one cannot study this report nor visit the institute without being greatly impressed with their methods.
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| Again using Harvard as our best example of an anatomical department with which to compare that in Munich, we find in each two eminent men as professors, and the entire teaching staff nimibers about the same in each. However, we find at Miinich from ten to twenty times as many students to be taught anatomy as at Harvard. The total cost of teaching this subject at MUnich is by no means ten times as great as at Harvard but the equipment for teaching is much greater and the professors receive more than twice the salary that is paid at Harvard. It is clear that in Munich the teaching is fidly centralized in the hands of the professors who teach very large classes, while at Harvard it is in sections, and is largely individual and inductive. In Munich all of the elementary instruction is given by the professors, which is not the case in America generally. The Miinich method of instruction is more economical than ours, for there the salary of professors is large enough to induce eminent men to do practically all of the work. Therefore, the laboratory is built to aid the professor in his teaching, much more than other members of the staff.
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| Students who cannot help themselves in Munich are not stuflfed through a Nuremberg funnel; recitations and quizzes are unknown. The teaching is adjusted to the average student, but it is scientific and those who cannot comprehend it are not whipped into line. Just at this point they save enormously in energy and do not commit the sin of trying to make physicians out of the unworthy. Students who desire more instruction than is ^ven in the regular courses, that is, those of ability and originality, are given every encouragement (p. 48) . Those who cannot comprehend are constantly eliminating themselves, for they drop out, while the great men of medicine are developed from the group of talented students, through encouragement. It follows that students are not forever being pulled up by the roots to see whether they are growing, but a process of naturd selection is at work. Mutations, when recognized, are, however, always preserved.
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| What has been said above concerns the professors and the students whose work is located mainly in the center of the building at Munich. But one wing, which is a large laboratory in itself, is reserved for the staff and for research. Here we find the very soul of a laboratory, for it is here that the assistants and advanced students do their work. The greater part of the teaching is done at Miinich by the professors, which in a way protects the assistants whose responsibility is mainly to themselves and to science. They are not worked to death with routine teaching but are permitted to become scientific anatomists, and not drudges. IJnder these conditions the finest spirit often permeates the entire staff, and for this the professor is largely responsible. After a professor has become well established, his desire for scientific work may wane. Those who have in them some spirit of altruism may continue to contribute to science, but the world, which is not inclined to believe in ideal motives, confounds this with self-seeking ambition. To the extent one's work is reflected in one's pupils and not in one's own publications, to that extent the motive certainly is altruistic. To carry out this ideal the large research wing of the institute exists and it is to be hoped that the altruistic spirit of DoUinger will continue to live in this anatomical palace for generations to come.
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| Franklin P. Mall.
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| {{Footer}} | | {{Footer}} |
Reinke EE. Note on the presence of the fifth aortic arch in a 6 mm pig embryo. (1910) Anat. Rec. 4: 453-.
Template:Historical Disclaimer
Note on the Presence of the Fifth Aortic Arch in a 6 mm Pig Embryo
Edwin E. Reinke
From The Laboratory Of Comparative Anatomyf Princeton University
Three Figures
In a paper printed in 1906, F. T. Lewis, after reviewing the observations recorded by previous authors and those made by himself, came to the conclusion that The interpretation of the postbranchial body in mammals as a fifth pouch, and of the irregular vessels in front of it as a fifth arch are morphological speculations of much interest, in favor of which the preceding observations afford no certain evidence." The same author had also made the statement in a previous article that The irregular small arteries around the fourth entoderm al pouch do not, as Zimmermann believed, form a distinct aortic arch." To this view W. A. Locy has taken exception.
In 1907, Locy summarized the observations upon the vascular elements between the fourth and sixth arches as follows: " (a) A complete arch as an offshoot of the fourth and returning to it, (human, Zimmermann) ; (b) a complete arch connecting the fourth and pulmonic arches, (pig, Lehmann, Locy; rat, Tandler); (c) a complete arch from the truncus arteriosus to the pulmonic arch, (human, two cases, Tandler) ; (e) irregular vascular elements from the fourth arch, the aortic root and the pulmonary arch, (pig, Lehmann, Lewis; rabbit, Lewis, Lehmann; rabbit, in stages of degeneration of the arch, Zimmermann) ; and (f ) a single vessel from the distal end of the pulmonic arch with unknown ventral connection, (sheep, Tandler)." Locy then adds, in opposition to the position of Lewis : " In the light of these observations it would appear that the vascular elements between the fourth and pulmonary arch exhibit great variability, but there are recorded a sufficient number of cases of their aggregation into a complete vessel to justify the assumption that there is a fifth aortic arch in mammals, as in other vertebrates."
In looking over the Princeton series no. 126 of a 6 mm. pig, it seemed to me that there was present a fifth aortic arch on both sides of the embryo. In order to confirm this opinion, at the suggestion of Prof. C. F. W. McClure, a wax reconstruction was made, and such was clearly seen to be the case on the right side at least. As shown in fig. 1,^ the first arch has already undergone considerable degeneration, while the second has almost entirely disappeared. The third, fourth and pulmonary arches are quite normal; the fourth is the largest, and the pulmonary has begun to give off the pulmonary artery. On the right side of the embryo there is a fifth arch which arises independently and connects with the fourth arch shortly before the latter enters the dorsal aorta.
This arch arises almost midway between the fourth and the sixth arches, there being a broad connection between its base and the fourth arch. It runs obliquely for a short distance from the aortic root toward the sixth arch and then turns at right angles to enter the fourth arch; but just before doing so it is connected dorsally with the sixth arch. From the turn on it narrows gradually up to a point just before its entrance into the fourth arch where it broadens out once more ; this fact together with its beaded appearance would indicate the beginning of degeneration.
In the light of the work of Evans upon the development of the aortae a very interesting interpretation can be placed upon the structure of the fifth arch as shown here. Considering the connections between the fifth arch and the fourth and the sixth arches as enclosing foramina and taking into account a third foramen that lies in the arch itself, we have at the dorsal end of the arch the remains of a capillary plexus whose vessels are of a relatively large caliber; all traces of it at the ventral end have been lost. It is from this plexus that the arch arose. At its dorsal end the formation of a single vessel from the plexus is not completed, although the main channel is clearly marked out. At the ventral end, on the other hand, not only has the single main vessel been established, but degeneration has already set in, this being due to the fact that most of the blood passes through the fourth arch. This disuse of the fifth arch would naturally cause the degeneration of the ventral half of the vessel very soon after its forir ation, in fact probably before the dorsal half has been fully crystallized out. Moreover, there is no reason to believe that this process of crystallization would continue at the dorsal end after degeneration had once commenced below.
- My thanks are due to Mr. O. F. Kampmeier who kindly made the drawing from the reconstruction, and to Mr. C. F. Sylvester for helping me with the microphotographs.
Fig. 1 Reconstruction of the pharynx and aortic arches of a 6 mm. pig embryo. Princeton Embryological Collection No. 126. Right side.
Fig. 2 A 6 mm. pig, Princeton Embryological collection, series 126, section no. 98. This section, through the region of the pharynx, sho^s the fourth pharyngeal pouch and the five ectodermal grooves on the right side. The fifth arch is seen in cross section just below the right dorsal aorta.
To my mind this affords a very clear explanation of why so many instances have been observed of irregular vascular elements lying between the fourth and the pulmonary arch and for the most part connected with the aortic root. The embryos were probably killed after the ventral portion of the arch had degenerated, or perhaps, as was most probably the case, the plexus had disappeared at that point without having formed a single main channel. But it is to be noted that very probably the broad portion of the fifth arch at the point where it joins the fourth arch is to a
Fig. 3 A 6 mm. pig, Princeton Embryological collection series No. 126, section 102. This section shows the five ectodermal grooves more clearly than they are shown in fig. 2. The fifth pouch on the right side s seen to correspond to the fifth groove. The fifth arch is also shown here in cross section but further away from the right dorsal aorta than shown in fig. 2.
certain extent comparable to the spurs described by Coulter in the cat embryo. Its persistence would seem to indicate that whether or no a main channel is formed from the plexus there is a stimulus for the blood to flow in that direction.^ On the left side of this embryo the appearance of the vascular elements reserr.bles in general some of the cases described by Miss Lehmann, there
In this particular case there can be no doubt that the channel formed was used as an actual blood passage, as blood corpuscles were found to be present in it.
being a narrower and shorter vessel running from the aortic root to the fourth arch, together with other small and irregular vascular remnants. Here, where in all probability a main channel was never formed, there is a spur on the fourth arch similar and corresponding to the broadened ventral end of the fifth arch on the right side.
In further support of the statement that we are dealing here with a complete fifth arch is the fact that there are five pharyngeal pouches present, between the fourth and fifth of which lies the arch. In the paper mentioned above, Mis3 Lehmann also described five pouches, but Lewis is inclined to doubt that the postbrancheal body (fifth pouch) arose as a true pharyngeal pouch. It is true, as he points out, that the fifth pouch never comes into contact with the ectoderm, but here there is very strong evidence that it is a true pouch. On the right side of the embryo from which the reconstruction was drawn there are five distinct ectodermal grooves present, one corresponding to each pharyngeal pouch. It is to be noted that the five grooves are found on the same side as the complete fifth arch, while on the left side, where there is a smaller and less complete arch, only four ectodermal grooves are to be seen. This is shown in figs. 2 and 3, which are photographs of two transverse sections, 15 micra thick, through the region of the pharynx. Fig. 2 shows the fourth pouch on the right side in contact with the ectoderm as well as the five ectodermal grooves. Fig. 3 gives a clearer view of the five grooves and also shows the fifth pouch almost in its entirety. Other 6 mm. pig series of the Princeton collection were examined, but none of them showed either five ectodermal grooves or a complete fifth arch on either side. This one clear case, however, of the presence of a fifth ectodern al groove, together with the well known fact that the fourth pouch and the postbranchial body arise from the pharynx independently of each other, indicates that the latter was originally a true pharyngeal pouch, i.e., the fifth.
It is clear that here we have a series of sections of a 6 mm. pig which is particularly advantageous. On the right side of the embryo not only is there a more complete fifth arch than has hitherto been described for the pig, but there are also five pharyngeal pouches and five ectodermal grooves corresponding to them. The left side, on the other hand, shows an arrangement of the vascular elements and the pharyngeal pouches which resembles in general those described by previous writers. In view of this evidence the existence of a complete fifth arch in the pig can hardly be called into question any longer and, in the opinion of the writer, those vascular elements so frequently found between the fourth and the sixth arches must be interpreted as the remnants either of a fully developed or a potential fifth arch.
Bibliography
Coulter C. B. 1009 The early development of the aortic arches of the cat, with especial reference to the presence of a fifth arch. Anat. Rec.,voI. 3, no. 11.
Evans, H. N. 1909 On the development of the aortae, cardinal and umbilical veins and other blood vessels of vertebrate embryos from capillaries. Anat. Rec, vol. 3, no. 9.
Lbhmann, Harbiet 1905 On the embryonic history of the aortic arches in mammals. Anat. Ans., Bd. 26, figs. 11 and 12.
Lewis, F. T. 1903 The intra-embryonic blood-vessels of rabbits from eight and one-half to thirteen days. Amer. Jour. Anat., vol. 3, (Abstract) . 1906 The fifth and sixth aortic arches and the related pharyngeal pouches in the rabbit and pig. Paper read before the Amer. Assoc, of Anatomists, Dec. 28, 1905. Published: Anat. Anz., Bd. 28.
LocT, W. A. 1907 The fifth and sixth aortic arches in birds and mammals. Proo. of the Seventh Intemat. Zodl. Congress.
Verdun, P. 1898 D^riv^s branchiaux, Toulouse, p. 178.
Cite this page: Hill, M.A. (2024, April 16) Embryology Paper - Note on the presence of the fifth aortic arch in a 6 mm pig embryo (1910). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Note_on_the_presence_of_the_fifth_aortic_arch_in_a_6_mm_pig_embryo_(1910)
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