Paper - On the origin of the pulmonary arteries in mammals: Difference between revisions

From Embryology
(Created page with "on the origin of the pulmonary arteries in mammals B? JOHN LEWIS BREMBR M. D. From tlce Emorxzosogicaz Lade-access, oj Harima-d ilfcdicac salicis-E. WITH 9 Tnxr Preuss-s....")
 
 
(6 intermediate revisions by the same user not shown)
Line 1: Line 1:
on the origin of the pulmonary arteries in mammals
{{Header}}
{{Ref-Bremer1902}}
{| class="wikitable mw-collapsible mw-collapsed"
! Online Editor 
|-
| [[File:Mark_Hill.jpg|90px|left]] This historic 1902 paper by Bremer describes development pulmonary of arteries.
<br>
See also {{Ref-Bremer1909}}
<br>
<br>
'''Modern Notes:'''
<br>
{{Heart Links}}
<br>
{{Respiratory Links}}
|}
{{Historic Disclaimer}}
==I. On the Origin of the Pulmonary Arteries in Mammals==


B?
By


JOHN LEWIS BREMBR M. D.
[[Embryology History - John Bremer|John Lewis Bremer]]
From tlce Emorxzosogicaz Lade-access, oj Harima-d ilfcdicac salicis-E.


WITH 9 Tnxr Preuss-s.
From the Embryological Laboratories of Harvard Medical School, Boston, Mass.


The material used in preparing this paper is from the collection of
With 9 Text Figures.
the Laboratory of Embryology at the Harvard Medical Scheel; the original number-s of the series and Sections have been preserved. The drawings are from reconstructions, and represent, as it were, casts of the
lumina of the arteries without referenoe to the thickness of their walls.
They are all of the same magnification ()( 80 diameters); the arteries
are seen from behind, a.nd the pulmonary arches can be followed until
they unite to form the truncus pulmonalis, or until, as in Fig. 1, they
enter the heart itself.


1n 1857, I-I. Rathke published his monograph, «D«ic Aortcnwässzcln
und die von, Ohne« easy-abends«- Artersien des« Bankiers« in which appear
the diagrams of the aortic arches now made more familiar by their repro
duction by Kölliker, Hertwig, Quer-in, and many others, with or without


slight modificationa In these diagrams the right and left pulmonary
==Introduction==
arteries are represented as arising, in lizasrds and birds, from their re—
spective fifth, or pulmonary, arches, while in snakes and in mammals
one fifth arch alone gives rise to both pulmonary arteries, the other arch
becoming obliteratedz in snakes the right pulmonetry arch remains, in
mammals the left. since this monograph there has been, so far as I
know, no Special investigation into the origin of the pulmonary arteries.


The ear1iest buds of the pulmonary arteries, in the rabbit, appear in
The material used in preparing this paper is from the collection of the Laboratory of Embryology at the Harvard Medical School; the original numbers of the series and Sections have been preserved. The drawings are from reconstructions, and represent, as it were, casts of the lumina of the arteries without referenoe to the thickness of their walls. They are all of the same magnification ()( 80 diameters); the arteries are seen from behind, and the pulmonary arches can be followed until they unite to form the truncus pulmonalis, or until, as in Fig. 1, they enter the heart itself.
embryo-s of about 4.0 mm., one bud from each of the psnlmonary arches,
on the mesial aspect of each. The growth of these buds is at first backward, then downward and inward, giving a small twist, Figs. It, L, Z, X,
near the proximal end of the pulmonary artery, which seems peculiar to
the ra-bbit. From this weist, the course is straight downward, on each
side of the trachea and slightly anterior t.o it, to the lungs, where the
usua.l branches are given ofk. During this downward course no branches
138 0n the Origin of the Pulmonary Arteries in Mamnials


are seen. As the arteries increase in length their proximal ends, where
they arise from the aortic arches, seem to approach each other actually,
as can be seen by comparing Figs. 1, 2 and Z. The mechanism of this
change is prosbably as follows: the truncns pulmonalis is at first short,
soon dividing into its two manches, the right and left jifth aortic archesz
as it becomes twisted are-und the aorta, following the turn of the heart,
the trnncus pulmonalis pulls on the two fifth arches, which are thus
crowded together, forming a, double tube, and at the same time the two
pulmonary a.rteries, arising from the mesial aspect of the two arches, are


· B.
1n 1857, I-I. Rathke published his monograph, «D«ic Aortcnwässzcln und die von, Ohne« easy-abends«- Artersien des« Bankiers« in which appear the diagrams of the aortic arches now made more familiar by their repro duction by Kölliker, Hertwig, Quain, and many others, with or without slight modificationa In these diagrams the right and left pulmonary arteries are represented as arising, in lizasrds and birds, from their respective fifth, or pulmonary, arches, while in snakes and in mammals one fifth arch alone gives rise to both pulmonary arteries, the other arch becoming obliteratedz in snakes the right pulmonetry arch remains, in mammals the left. since this monograph there has been, so far as I know, no special investigation into the origin of the pulmonary arteries.
X -.
XI
««-EJ" Ziff-M
ttktsilxjr
«· tin.
E l


Wulst! i titviktsul


iuuutis ummttttktlllkttksttt
The ear1iest buds of the pulmonary arteries, in the rabbit, appear in embryos of about 4.0 mm., one bud from each of the psnlmonary arches, on the mesial aspect of each. The growth of these buds is at first backward, then downward and inward, giving a small twist, Figs. It, L, Z, X, near the proximal end of the pulmonary artery, which seems peculiar to the ra-bbit. From this weist, the course is straight downward, on each side of the trachea and slightly anterior t.o it, to the lungs, where the usua.l branches are given ofk. During this downward course no branches are seen. As the arteries increase in length their proximal ends, where they arise from the aortic arches, seem to approach each other actually, as can be seen by comparing Figs. 1, 2 and Z. The mechanism of this change is prosbably as follows: the truncns pulmonalis is at first short, soon dividing into its two manches, the right and left jifth aortic archesz as it becomes twisted around the aorta, following the turn of the heart, the trnncus pulmonalis pulls on the two fifth arches, which are thus crowded together, forming a, double tube, and at the same time the two pulmonary arteries, arising from the mesial aspect of the two arches, are brought nearer to-gether. By fnsion of the two parallel arches the trnncus pulmonalis is increased in length, and its-two branches shortss enedz this fusion may extend until the origins of the pnlmonaisy arteries are very near the bifurcation, or until the left artery springe actually from the bifurcation.


Frei. 1. Fuss. L.


Frei. 1. Rabbit of 5.0 mm. Frontal series No. 148, Sections 250-261.
)( 80 diameter-s. A, B, left and right pnlmonary arches, opening directly
into heart, H. c, D, pulmonkiry arteries. F, G, kourth aortic arohes,


opening into Idee-Ist.
Fig. 1. Rabbit of 5.0 mm. Frontal series No. 148, Sections 250-261. )( 80 diameter-s. A, B, left and right pnlmonary arches, opening directly into heart, H. c, D, pulmonkiry arteries. F, G, fourth aortic arches, opening into Idee-Ist.  
Fig. 2. Rabbit of. 8.0 nun. Frontal series No. 154, Sections 291—311. )( 80
diameter-s. B, junction of A and B. H, valve of heart.


brought nearer to-gether. By fnsion of the two parallel arches the
trnncus pulmonalis is increased in length, and its-two branches shortss
enedz this fusion may extend until the origins of the pnlmonaisy arteries
are very near the bifurcation, or unt.il the left artery springe actually
from the bifurcation


The dia.meter of the pulmonary art-eries remains small in comparison
Fig. 2. Rabbit of. 8.0 mm. Frontal series No. 154, Sections 291—311. )( 80 diameter-s. B, junction of A and B. H, valve of heart.
to their increasing length, as one might expeot from the slight necessity
John Lewis Bremer 139


of blood in the unused lungs. The left pulmonary arch grows rapidly
in diameter as well as in length, while the right becomes entirely oblit—
erated beyond the point vvhere the pulmonary artery arises, leaving
finally no trace of its existenoez from this point to the junction with
the left arch to form the truncus pu1monalis, the right arch remains
of the same oalibre as the pulmonary artery. The small twist inarking
the origin of the pulmonary artery gradually straightens out, and the
whole right side, es. e. the anterior portion of the fifth arch fand the


A
x X . a F·
M «· « W« S
x ·
c V
l «· g
» E
- E
H« E
» E
«
E
S ?7 E
E
Frei. Z.


Frei. 4.


pro. Z. Rabbit of 10.0 kam. Frontal series No. 157, Sections 347-367.
The diameter of the pulmonary art-eries remains small in comparison to their increasing length, as one might expeot from the slight necessity of blood in the unused lungs. The left pulmonary arch grows rapidly in diameter as well as in length, while the right becomes entirely obliterated beyond the point vvhere the pulmonary artery arises, leaving finally no trace of its existenoez from this point to the junction with the left arch to form the truncus pu1monalis, the right arch remains of the same oalibre as the pulmonary artery. The small twist inarking the origin of the pulmonary artery gradually straightens out, and the whole right side, es. e. the anterior portion of the fifth arch and the pulmonaxry artery, being now unattached to the right dorsal aorta, is drawn to the left by the larger left aortic arch, which is constantly tending to become straight As a result of these changes, the left pulmonary areh seems to give rise, at about its mid-point, to two arteries, with their origins close together (or there may be a very short common stem); the right one, the longer of the two, arising anteriorly, and talcing its course at first almost horizontally across to the right side of the trachea, then bending down toward the right lang, the left pursuing a straight course to the left lung. The portion of the left jifth arch posterior to the pulmonary arteries becoimes later the Ductus Botalli, and is closed at birth.


X 80 diam eters.


Fig. 4. Pig of "7.8 Ihm. Frontal series No. 430, Sections 270-297. X 80
diameters


pulmonaxry artery, being now unattached to the right dorsal aorta, is
Fig. 3. Rabbit of 10.0 mm. Frontal series No. 157, Sections 347-367. X 80 diameters.
drawn to the left by the larger left aortic arch, which is constantly tending to become straight As a result of these changes, the left pulmonary
areh seems to give rise, at about its mid—point, to two arteries, with their
origins close together (or there may be a very short common stem); the
right one, the longer of the two, arising anteriorly, and talcing its course
140 0n the Origin of the Pulmonary Arteries in Mammals


at first almost horizontally across to the right side of the trachea, then
Fig. 4. Pig of 7.8 mm. Frontal series No. 430, Sections 270-297. X 80 diameters
bending down toward the right lang, the left pursuing a straight course
to the left lung. The portion of the left jifth arch posterior to the
pulmonary arteries becoimes later the Ductus Botalli, and is closed at
birth.


It will be seen from this description that, in the actual origin of the
pulmonary arteries, the rabbit is identical with birds and repti1es, as
drawn by Rathke and verified by many other writers. In the rabbit, as
well a-s in birds and reptiles, one pulmonary artery arises from each
pulmonary arch, but in birds and reptiles the growth of these arches
is equal until birth, so that the picture is symmetrica1, a fifth arch, a
pulmonary artery, and a Ductus Botalli on each sidez while in the
rabbit the left pulmonary arch alone remains until birth, and the pieture is distorted It was this distortion, this early disappearance of
that portion of the right pulmonary arch posterior to the pulmonary
artery, which made possib1e the diagram of Rathke, and his statement
that « in mammals the left fifth a-o1·tic arch at a. very early period of
embryonic life sends out from about its mid—point a small branch which
is intended for both lungs, and posterior to its place of origin divides
into two twigsk


Bathlce examined, of mammals, the pig, sheep, and hare, with Special
reference to the pulmonary arteriesf In the rabb-it, cat, and in the
few human embryos within my reach, I have found the pulmonary
arteries to arise as I have stated, that is, in the beginning, symmetrica11y,
one from each pulmonary arch. In Rathke’s original diagrains the
arteries of lizards and of birds arise symmetrica.lly, as do they also in the
frog, as described by Gauppsz Of snakes, according to stannius and
others, while most species have only the right lung, and therefore only
the right pulmonary artery, in adult life, some species have the left
lung and left artery alone, and others even both lungs and both arteries,
more or less fully developed In two cases, recently cited by F. Hoch—
Stett-ers of Tropidonotus tessellatus (a) specie-s vxsith only the right lung
normally developed), a slender a.rte-ry was found, which, although iinally
ramifying in the oesophageal Wall, resemb1ed in origin and course a left
pulmonary artery. From these fa.cts it seems probable that in the
younger snake embryos, of all species, both pulmonary arteries will be
found present. If this is the case, the proof will be streng that, in all


1Miiller’s Archiv, 1843, P. 276.
It will be seen from this description that, in the actual origin of the pulmonary arteries, the rabbit is identical with birds and repti1es, as drawn by Rathke and verified by many other writers. In the rabbit, as well a-s in birds and reptiles, one pulmonary artery arises from each pulmonary arch, but in birds and reptiles the growth of these arches is equal until birth, so that the picture is symmetrica1, a fifth arch, a pulmonary artery, and a Ductus Botalli on each sidez while in the rabbit the left pulmonary arch alone remains until birth, and the pieture is distorted It was this distortion, this early disappearance of that portion of the right pulmonary arch posterior to the pulmonary artery, which made possib1e the diagram of Rathke, and his statement that in mammals the left fifth aortic arch at a very early period of embryonic life sends out from about its mid—point a small branch which is intended for both lungs, and posterior to its place of origin divides into two twigs.
I Anatomie des Frosohea diagram, P. 285.
3 ltiotsphologisches Jahrbucln 1901, p. 419.
John Lewis Bremer 141


vertebrates with lungs the pulmonary arteries originate one from each
pulmonary areh, and that Rathkcsks djagra.m«s, thongh describsing per—
feotly the adu1t and 1ate embryonie eonditions, are, as regards this origin,
inoorreot


In the Fig, one of the animals examined by Rathke, although the
Bathlce examined, of mammals, the pig, sheep, and hare, with special reference to the pulmonary arteries. In the rabbit, cat, and in the few human embryos within my reach, I have found the pulmonary arteries to arise as I have stated, that is, in the beginning, symmetrica11y, one from each pulmonary arch. In Rathke’s original diagrains the arteries of lizards and of birds arise symmetrica.lly, as do they also in the frog, as described by Gauppsz Of snakes, according to stannius and others, while most species have only the right lung, and therefore only the right pulmonary artery, in adult life, some species have the left lung and left artery alone, and others even both lungs and both arteries, more or less fully developed In two cases, recently cited by F. Hoch— Stett-ers of Tropidonotus tessellatus (a) specie-s vxsith only the right lung normally developed), a slender artery was found, which, although iinally ramifying in the oesophageal Wall, resemb1ed in origin and course a left pulmonary artery. From these fa.cts it seems probable that in the younger snake embryos, of all species, both pulmonary arteries will be found present. If this is the case, the proof will be streng that, in all vertebrates with lungs the pulmonary arteries originate one from each pulmonary areh, and that Rathke's diagrams, thongh describsing perfectly the adu1t and 1ate embryonic conditions, are as regards this origin, incorrect.
symmetrieaä origin is preserved, one pulmonary artery arising from each
pujmonarsy Stroh, and although the nltimate appearanoe, that of both


Fig. 6.


Frass. 5. Pig of 9.0 mm. Frontal series No. 54, Sections 462—502. )( 80
diameters.


Fuss. 6. Pig of 11.0 nun. Sagittal series No. 8, Sections 96-113. X 80
* 1. Miiller’s Archiv, 1843, P. 276.
diameters.
* 2. Anatomie des Frosohea diagram, P. 285.  
* 3. ltiotsphologisches Jahrbuch 1901, p. 419.


pulmonary arteries arising from the mid-point of the left piulmonary
aroh, is the same as in the other mammals I have examined, the intermediate steps are different, as is shown in Figa 4 to 9. Instead of
remaining comparatively parallel, as in the rabbit, the pulmonary arteries, after attaining considerable length (pig of 7.8 mm.), bend toward
142 0n the Origin of the Pulmonary Arteries in Mammals


eaeh other, and insteaci of remaining without branohes (exeept those
In the Pig, one of the animals examined by Rathke, although the symmetrieaä origin is preserved, one pulmonary artery arising from each pujmonarsy Stroh, and although the nltimate appearanoe, that of both pulmonary arteries arising from the mid-point of the left piulmonary aroh, is the same as in the other mammals I have examined, the intermediate steps are different, as is shown in Figa 4 to 9. Instead of remaining comparatively parallel, as in the rabbit, the pulmonary arteries, after attaining considerable length (pig of 7.8 mm.), bend toward each other, and insteaci of remaining without branohes (exeept those deve1oped later in the lange) send out buds, each toward the other artery, Fig. 4, X, II. This bending toward the median line of these two pulmonaxry arteries is perhaps eaused by the great growth of the aurieles of the heascst in the Fig. Both processes continue until in a pig of 9 mm. there is at 1east one eonneetion between the right and Ieft pulmonary arteries, often two, as is snggested in Fig. 5, X, F, while in a pig of 11.0 mm. the two arteries, along a considerable part of their length, have merged into one channel, Fig. 6. Meanwhile the npper or proximal part of the right pulmonary arterzg which often shows signs of irregu1arity, such as a double origin, Figs. 4 and 7, D, ceases to increase in size, then grows sma11er, and soon becomes obliterated, so that all the blood to both lnngs Hows through the left puhnonary arterzn This gradual change is shown at D, Figa 5, 6 and 7, and in Fig. Z. where only the remains of the right artery are seen. For a 1ittle while after the obliteration of the lumen, a cord of connective tissue marks the  former course of the right pulmonary artery, but soon even this disappears.
deve1oped later in the lange) send out buds, each toward the other
artery, Fig. 4, X, II. This bending toward the median line of these two




Fuss. 7. Pig of 12.0 mai. Transverse series No. s,
Sections 366-404. X 80 d,ia-meters.






Fuss. s. Pig of 12.0 nun. Prontal series No. S, Sections 429-464. X 80
Fig. 5. Pig of 9.0 mm. Frontal series No. 54, Sections 462—502. x 80 diameters.
diameters.


pulmonaxry arteries is perhaps eaused by the great growth of the aurieles
Fig. 6. Pig of 11.0 mm. Sagittal series No. 8, Sections 96-113. X 80 diameters.
of the heascst in the Fig. Both processes continue until in a pig of
9 mm. there is at 1east one eonneetion between the right and Ieft pulJohn Lewis Bremer 143


monary arteries, often two, as is snggested in Fig. 5, X, F, while in a
pig of 11.0 mm. the two arteries, along a considerable part of their
length, have merged into one channel, Fig. 6. Meanwhile the npper or
proximal part of the right pulmonary arterzg which often shows signs of


F1G. 9. Pig of 20.0 nun. Frontal series No. 61, Sections 270-279. X 80
Fig. 7. Pig of 12.0 mm. Transverse series No. s, Sections 366-404. x 80 d,ia-meters.
diameters


irregu1arity, such as a double origin, Figs. 4 and 7, D, ceases to increase
in size, then grows sma11er, and soon becomes obliterated, so that all
the blood to both lnngs Hows through the left puhnonary arterzn This
gradual change is shown at D, Figa 5, 6 and 7, and in Fig. Z. where
only the remains of the right artery are seen. For a 1ittle while after
the obliteration of the lumen, a cord of connective tissue marks the
144 0n the 0rigin of the Pulmonary Arteries in Mainmals


former course of the right pulmonary artery, but soon even this disappears.
Fig. 8. Pig of 12.0 mm. Prontal series No. S, Sections 429-464. X 80 diameters.


Along with this change, another, common to all mammals, has taken
place, naInely, the obliteration of the right pulmonary archz but this
is not the cause of the obliteration of the right pulmonary artery, since
the lumen of the latter is the first to close, Fig. 8. Still another change
is seen, as in the rabbit, in the lengthening of the truncus pulmonalis
at the expense of the two pulmonary arches, and the oonsequent appars
ent movement of the left pulmonary artery toward the right pulmonary
arch. In the pig, considerable variation seems to occur in regard to
the sta-ge of growth at which this last mentioned change takes place, as
may be seen by comparing Figs 6 and 7, where the distance between
the points of origin of the pulmonary arteries is about the same in
two pigs of 11.0 and 12.0 mm., respectively, and Fig. 8, where the
distance is much greater, although the length of the eInbryo is again
12.0 mm. 1t will be seen that of the two 12.0 Ihm. pigs, one still
has, and one has already lost, the connection of the right pulmonary
artery.


Whether all ungulates, or only pigs, have this odd method of arriving
 
at the adult relations of the pulmona.ry arteries, I do not as yet know;
Fig. 9. Pig of 20.0 mm. Frontal series No. 61, Sections 270-279. X 80 diameters
ce1·ta.inly there is nothing like it in the rabbit, the cat, the dog, or in
 
the human embryos within my reach.
 
 
Along with this change, another, common to all mammals, has taken place, naInely, the obliteration of the right pulmonary archz but this is not the cause of the obliteration of the right pulmonary artery, since the lumen of the latter is the first to close, Fig. 8. Still another change is seen, as in the rabbit, in the lengthening of the truncus pulmonalis at the expense of the two pulmonary arches, and the oonsequent appars ent movement of the left pulmonary artery toward the right pulmonary arch. In the pig, considerable variation seems to occur in regard to the sta-ge of growth at which this last mentioned change takes place, as may be seen by comparing Figs 6 and 7, where the distance between the points of origin of the pulmonary arteries is about the same in two pigs of 11.0 and 12.0 mm., respectively, and Fig. 8, where the distance is much greater, although the length of the eInbryo is again 12.0 mm. 1t will be seen that of the two 12.0 Ihm. pigs, one still has, and one has already lost, the connection of the right pulmonary artery.
 
 
Whether all ungulates, or only {{pig}}s, have this odd method of arriving at the adult relations of the pulmonary arteries, I do not as yet know; certainly there is nothing like it in the {{rabbit}}, the {{cat}}, the {{dog}}, or in the human embryos within my reach.
 
 
 
[[Category:1900's]][[Category:Cardiovascular]][[Category:Respiratory]][[Category:Blood Vessel]]
[[Category:Draft]]

Latest revision as of 12:32, 10 August 2018

Embryology - 28 Mar 2024    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)

Bremer JL. On the origin of the pulmonary arteries in mammals. (1902) Amer. J Anat. 1(2): 135-

Online Editor 
Mark Hill.jpg
This historic 1902 paper by Bremer describes development pulmonary of arteries.


See also Bremer JL. II. On the origin of the pulmonary arteries in mammals. (1909) Amer. J Anat.

Modern Notes:

Cardiovascular Links: cardiovascular | Heart Tutorial | Lecture - Early Vascular | Lecture - Heart | Movies | 2016 Cardiac Review | heart | coronary circulation | heart valve | heart rate | Circulation | blood | blood vessel | blood vessel histology | heart histology | Lymphatic | ductus venosus | spleen | Stage 22 | cardiovascular abnormalities | OMIM | 2012 ECHO Meeting | Category:Cardiovascular
Historic Embryology - Cardiovascular 
1902 Vena cava inferior | 1905 Brain Blood Vessels | 1909 Cervical Veins | 1909 Dorsal aorta and umbilical veins | 1912 Heart | 1912 Human Heart | 1914 Earliest Blood-Vessels | 1915 Congenital Cardiac Disease | 1915 Dura Venous Sinuses | 1916 Blood cell origin | 1916 Pars Membranacea Septi | 1919 Lower Limb Arteries | 1921 Human Brain Vascular | 1921 Spleen | 1922 Aortic-Arch System | 1922 Pig Forelimb Arteries | 1922 Chicken Pulmonary | 1923 Head Subcutaneous Plexus | 1923 Ductus Venosus | 1925 Venous Development | 1927 Stage 11 Heart | 1928 Heart Blood Flow | 1935 Aorta | 1935 Venous valves | 1938 Pars Membranacea Septi | 1938 Foramen Ovale | 1939 Atrio-Ventricular Valves | 1940 Vena cava inferior | 1940 Early Hematopoiesis | 1941 Blood Formation | 1942 Truncus and Conus Partitioning | Ziegler Heart Models | 1951 Heart Movie | 1954 Week 9 Heart | 1957 Cranial venous system | 1959 Brain Arterial Anastomoses | Historic Embryology Papers | 2012 ECHO Meeting | 2016 Cardiac Review | Historic Disclaimer


Respiratory Links: respiratory | Science Lecture | Lecture Movie | Med Lecture | Stage 13 | Stage 22 | upper respiratory tract | diaphragm | Histology | Postnatal | respiratory abnormalities | Respiratory Quiz | Respiratory terms | Category:Respiratory
Historic Embryology - Respiratory 
1902 The Nasal Cavities and Olfactory Structures | 1906 Lung | 1912 Upper Respiratory Tract | 1912 Respiratory | 1913 Prenatal and Neonatal Lung | 1914 Phrenic Nerve | 1918 Respiratory images | 1921 Respiratory | 1922 Chick Pulmonary Vessels | 1934 Right Fetal Lung | 1936 Early Human Lung | 1937 Terminal Air Passages | 1938 Human Histology
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)

I. On the Origin of the Pulmonary Arteries in Mammals

By

John Lewis Bremer

From the Embryological Laboratories of Harvard Medical School, Boston, Mass.

With 9 Text Figures.


Introduction

The material used in preparing this paper is from the collection of the Laboratory of Embryology at the Harvard Medical School; the original numbers of the series and Sections have been preserved. The drawings are from reconstructions, and represent, as it were, casts of the lumina of the arteries without referenoe to the thickness of their walls. They are all of the same magnification ()( 80 diameters); the arteries are seen from behind, and the pulmonary arches can be followed until they unite to form the truncus pulmonalis, or until, as in Fig. 1, they enter the heart itself.


1n 1857, I-I. Rathke published his monograph, «D«ic Aortcnwässzcln und die von, Ohne« easy-abends«- Artersien des« Bankiers« in which appear the diagrams of the aortic arches now made more familiar by their repro duction by Kölliker, Hertwig, Quain, and many others, with or without slight modificationa In these diagrams the right and left pulmonary arteries are represented as arising, in lizasrds and birds, from their respective fifth, or pulmonary, arches, while in snakes and in mammals one fifth arch alone gives rise to both pulmonary arteries, the other arch becoming obliteratedz in snakes the right pulmonetry arch remains, in mammals the left. since this monograph there has been, so far as I know, no special investigation into the origin of the pulmonary arteries.


The ear1iest buds of the pulmonary arteries, in the rabbit, appear in embryos of about 4.0 mm., one bud from each of the psnlmonary arches, on the mesial aspect of each. The growth of these buds is at first backward, then downward and inward, giving a small twist, Figs. It, L, Z, X, near the proximal end of the pulmonary artery, which seems peculiar to the ra-bbit. From this weist, the course is straight downward, on each side of the trachea and slightly anterior t.o it, to the lungs, where the usua.l branches are given ofk. During this downward course no branches are seen. As the arteries increase in length their proximal ends, where they arise from the aortic arches, seem to approach each other actually, as can be seen by comparing Figs. 1, 2 and Z. The mechanism of this change is prosbably as follows: the truncns pulmonalis is at first short, soon dividing into its two manches, the right and left jifth aortic archesz as it becomes twisted around the aorta, following the turn of the heart, the trnncus pulmonalis pulls on the two fifth arches, which are thus crowded together, forming a, double tube, and at the same time the two pulmonary arteries, arising from the mesial aspect of the two arches, are brought nearer to-gether. By fnsion of the two parallel arches the trnncus pulmonalis is increased in length, and its-two branches shortss enedz this fusion may extend until the origins of the pnlmonaisy arteries are very near the bifurcation, or until the left artery springe actually from the bifurcation.


Fig. 1. Rabbit of 5.0 mm. Frontal series No. 148, Sections 250-261. )( 80 diameter-s. A, B, left and right pnlmonary arches, opening directly into heart, H. c, D, pulmonkiry arteries. F, G, fourth aortic arches, opening into Idee-Ist.


Fig. 2. Rabbit of. 8.0 mm. Frontal series No. 154, Sections 291—311. )( 80 diameter-s. B, junction of A and B. H, valve of heart.



The diameter of the pulmonary art-eries remains small in comparison to their increasing length, as one might expeot from the slight necessity of blood in the unused lungs. The left pulmonary arch grows rapidly in diameter as well as in length, while the right becomes entirely obliterated beyond the point vvhere the pulmonary artery arises, leaving finally no trace of its existenoez from this point to the junction with the left arch to form the truncus pu1monalis, the right arch remains of the same oalibre as the pulmonary artery. The small twist inarking the origin of the pulmonary artery gradually straightens out, and the whole right side, es. e. the anterior portion of the fifth arch and the pulmonaxry artery, being now unattached to the right dorsal aorta, is drawn to the left by the larger left aortic arch, which is constantly tending to become straight As a result of these changes, the left pulmonary areh seems to give rise, at about its mid-point, to two arteries, with their origins close together (or there may be a very short common stem); the right one, the longer of the two, arising anteriorly, and talcing its course at first almost horizontally across to the right side of the trachea, then bending down toward the right lang, the left pursuing a straight course to the left lung. The portion of the left jifth arch posterior to the pulmonary arteries becoimes later the Ductus Botalli, and is closed at birth.


Fig. 3. Rabbit of 10.0 mm. Frontal series No. 157, Sections 347-367. X 80 diameters.

Fig. 4. Pig of 7.8 mm. Frontal series No. 430, Sections 270-297. X 80 diameters


It will be seen from this description that, in the actual origin of the pulmonary arteries, the rabbit is identical with birds and repti1es, as drawn by Rathke and verified by many other writers. In the rabbit, as well a-s in birds and reptiles, one pulmonary artery arises from each pulmonary arch, but in birds and reptiles the growth of these arches is equal until birth, so that the picture is symmetrica1, a fifth arch, a pulmonary artery, and a Ductus Botalli on each sidez while in the rabbit the left pulmonary arch alone remains until birth, and the pieture is distorted It was this distortion, this early disappearance of that portion of the right pulmonary arch posterior to the pulmonary artery, which made possib1e the diagram of Rathke, and his statement that in mammals the left fifth aortic arch at a very early period of embryonic life sends out from about its mid—point a small branch which is intended for both lungs, and posterior to its place of origin divides into two twigs.


Bathlce examined, of mammals, the pig, sheep, and hare, with special reference to the pulmonary arteries. In the rabbit, cat, and in the few human embryos within my reach, I have found the pulmonary arteries to arise as I have stated, that is, in the beginning, symmetrica11y, one from each pulmonary arch. In Rathke’s original diagrains the arteries of lizards and of birds arise symmetrica.lly, as do they also in the frog, as described by Gauppsz Of snakes, according to stannius and others, while most species have only the right lung, and therefore only the right pulmonary artery, in adult life, some species have the left lung and left artery alone, and others even both lungs and both arteries, more or less fully developed In two cases, recently cited by F. Hoch— Stett-ers of Tropidonotus tessellatus (a) specie-s vxsith only the right lung normally developed), a slender artery was found, which, although iinally ramifying in the oesophageal Wall, resemb1ed in origin and course a left pulmonary artery. From these fa.cts it seems probable that in the younger snake embryos, of all species, both pulmonary arteries will be found present. If this is the case, the proof will be streng that, in all vertebrates with lungs the pulmonary arteries originate one from each pulmonary areh, and that Rathke's diagrams, thongh describsing perfectly the adu1t and 1ate embryonic conditions, are as regards this origin, incorrect.


  • 1. Miiller’s Archiv, 1843, P. 276.
  • 2. Anatomie des Frosohea diagram, P. 285.
  • 3. ltiotsphologisches Jahrbuch 1901, p. 419.


In the Pig, one of the animals examined by Rathke, although the symmetrieaä origin is preserved, one pulmonary artery arising from each pujmonarsy Stroh, and although the nltimate appearanoe, that of both pulmonary arteries arising from the mid-point of the left piulmonary aroh, is the same as in the other mammals I have examined, the intermediate steps are different, as is shown in Figa 4 to 9. Instead of remaining comparatively parallel, as in the rabbit, the pulmonary arteries, after attaining considerable length (pig of 7.8 mm.), bend toward each other, and insteaci of remaining without branohes (exeept those deve1oped later in the lange) send out buds, each toward the other artery, Fig. 4, X, II. This bending toward the median line of these two pulmonaxry arteries is perhaps eaused by the great growth of the aurieles of the heascst in the Fig. Both processes continue until in a pig of 9 mm. there is at 1east one eonneetion between the right and Ieft pulmonary arteries, often two, as is snggested in Fig. 5, X, F, while in a pig of 11.0 mm. the two arteries, along a considerable part of their length, have merged into one channel, Fig. 6. Meanwhile the npper or proximal part of the right pulmonary arterzg which often shows signs of irregu1arity, such as a double origin, Figs. 4 and 7, D, ceases to increase in size, then grows sma11er, and soon becomes obliterated, so that all the blood to both lnngs Hows through the left puhnonary arterzn This gradual change is shown at D, Figa 5, 6 and 7, and in Fig. Z. where only the remains of the right artery are seen. For a 1ittle while after the obliteration of the lumen, a cord of connective tissue marks the former course of the right pulmonary artery, but soon even this disappears.



Fig. 5. Pig of 9.0 mm. Frontal series No. 54, Sections 462—502. x 80 diameters.

Fig. 6. Pig of 11.0 mm. Sagittal series No. 8, Sections 96-113. X 80 diameters.


Fig. 7. Pig of 12.0 mm. Transverse series No. s, Sections 366-404. x 80 d,ia-meters.


Fig. 8. Pig of 12.0 mm. Prontal series No. S, Sections 429-464. X 80 diameters.


Fig. 9. Pig of 20.0 mm. Frontal series No. 61, Sections 270-279. X 80 diameters


Along with this change, another, common to all mammals, has taken place, naInely, the obliteration of the right pulmonary archz but this is not the cause of the obliteration of the right pulmonary artery, since the lumen of the latter is the first to close, Fig. 8. Still another change is seen, as in the rabbit, in the lengthening of the truncus pulmonalis at the expense of the two pulmonary arches, and the oonsequent appars ent movement of the left pulmonary artery toward the right pulmonary arch. In the pig, considerable variation seems to occur in regard to the sta-ge of growth at which this last mentioned change takes place, as may be seen by comparing Figs 6 and 7, where the distance between the points of origin of the pulmonary arteries is about the same in two pigs of 11.0 and 12.0 mm., respectively, and Fig. 8, where the distance is much greater, although the length of the eInbryo is again 12.0 mm. 1t will be seen that of the two 12.0 Ihm. pigs, one still has, and one has already lost, the connection of the right pulmonary artery.


Whether all ungulates, or only pigs, have this odd method of arriving at the adult relations of the pulmonary arteries, I do not as yet know; certainly there is nothing like it in the rabbit, the cat, the dog, or in the human embryos within my reach.