Difference between revisions of "Paper - A note on the developmental relations of the kidney and ureter in human embryos (1905)"

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=A note on the developmental relations of the kidney and ureter in human embryos=
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By Augustus G. Pohlman, M. D.,
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Assistant Professor of Anatomy, University of Indiana.
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==Introduction==
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The first signs of the permanent kidney (metanephros) is found in a dorsal outgrowth of the Wolffian duct close to its orifice in the cloaca. The Wolffian duct (segmental) reaches the caudal part of the enteron in embryo {{CE76}} (4.5 mm.). It is of even caliber throughout its course, dilating slightly as it enters the cloaca. As the duct comes into relation with the cloaca, two varieties of epithelium meet, the mesodermic epithelium of the duct and the entodermic of the gut. There must of necessity be an epithelial plate separating the duct from the cloaca, but it probably disappears with its formation.
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* This and other similar figures refer to the catalogue number in the Anatomical Collection of the Johns Hopkins Medical School.
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In the slightly older embryo {{CE80}} (5.0 mm.) the duct has given off a small shoot which arises dorsally and continues the lumen of the duct into the mesodermic tissue as yet undifferentiated, in which the whole is embedded. The lumen of this bud, the renal bud, is somewhat larger than that of the duct proper and is dilated toward its blind end. The surrounding tissue has become condensed about the end of the bud and is easily recognized by its different arrangement and by its darker stain with carmine. The renal anlage is placed at the second sacral vertebra as nearly as can be estimated, in the uncertainty of the vertebra at this stage and the difficulty in fixing the direction which might be called the right angle to the bent vertebral column. This position does not change until an older stage is reached as was verified in the models of embryo {{CE3}} (7.0 mm.) by Professor Mall and embryo {{CE163}} (9.0 mm.) by Professor Bardeen.
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The renal anlage may be divided into two distinct parts in embryo {{CE2}} (7.0 mm.) ; a segment not surrounded by specialized mesodermic tissue, the future ureter, and a segment capped by the specialized tissue, the renal mesenchyme, the kidney and all the derivatives of the bud included within the kidney substance. The two anlages, the right and left, point dorsally from their position on the Wolffian ducts and even converge toward the middle line, and approach each other so closely that it is a matter of 50 microns separating them. The buds are at the same level and the ureter and kidney segments are of equal size.
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In embryo {{CE88}} (9.0 mm.) the distal end of the bud undergoes a division into an upper and lower sprout which are enclosed in the renal mesenchyme and represent the future upper and lower pelves of the adult kidney. The renal mesenchyme in the meantime has developed in a vertical direction and is bean-shaped. Stationary up to this stage the kidney now begins a rapid wandering to its future permanent position in the body.
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The sharp division into an upper and lower sprout is lost in embryo 114 (10.0 mm.). The renal mass is distinctly bean-shaped in reconstruction and rather flattened from side to side. The hilum is situated ventrally. The ureter has elongated but is still in relation with the Wolffian duct dorsally. The kidneys are placed with their upper ends at the brim of the pelvis, the one a little higher than the other. The hilum of the kidney is well marked although the organ is as yet not vascularized. The two kidneys are placed with their long axes parallel and measure from tip to tip about 0.6 mm. and are about 0.2 mm. apart.
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The upper border of the developing kidney reaches the third lumbar vertebra in embryo {{CE144}} (14.0 mm.). The ureter still emerges from its ventral aspect, but the relations at the lower end have changed. The ureter is rotated to a lateral position on the Wolffian duct and that portion of the duct which lay between the bud and the cloaca has disappeared (?), bringing the orifice of the ureter directly at the cloaca or into the duct at the cloaca. The kidney is without blood supply and lies behind the Wolffian body.
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In embryo {{CE43}} (16.0 mm.) the kidney lies higher than in the preceding embryo. In addition it has imdergone an axial rotation bringing the hilum to its mesial border, i. e., turned about 90° toward the middle line. The ureter has acquired a distinct orifice into the ventral segment of the cloaca lateral to the orifice of the Wolffian duct. The cloaca is completely divided at this stage.
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The kidney arrives at its normal height in embryo {{CE22}} (20.0 mm.). The rotation is maintained and the kidneys, except that they lie closely together, are in the adult position. The vascularity is as yet problematic. In the meantime the ureter has lost all connection with the Wolffian duct and has grown into a higher and more lateral location as a fixed structure. The Miillerian ducts in this embryo are unusual in that the left duct has reached the urogenital sinus while the right lies a full slide higher up. The kidneys are about 1.0 mm. apart.
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Chronologically: The Wolffian duct joins the cloaca at 4.5 mm.; the renal buds appear at 5.0 mm.; the renal buds may be differentiated into two segments, the ureter and kidney, at 7.0 mm. when they lie opposite the second sacral vertebra ; at 10.0 mm. the upper border of the kidney is at the brim of the pelvis; at 14.0 mm. the ureter lies lateral to the Wolffian duct and the upper pole of the kidney is at the third lumbar vertebra ; at 16.0 mm. the kidney has passed the midlumbar line and has been rotated through 90° on its long axis while the ureter has a separate orifice in the urogenital sinus; at 20.0 mm. the ureter and kidney are in the relative noimal position and the Miillerian ducts have gained the sinus.
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 +
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The rotation of the kidney and the displacement of the ureter at the lower end, although they occur at the same time, are distinct processes. This may be demonstrated in cases of incomplete double ureter where the ureter is divided into two segments somewhere along its course. The ventral segment proceeds from the upper pelvis of the kidney, while the dorsal branch is connected with the lower pelvis. If there were any connection between the rotation of the kidney at the midlumbar line with the lateral displacement at the lower end of the ureter, there would be evidences of such rotation along the course of the anomalous branches of the ureter, but we find the position of the two segments, the one ventral to the other maintained even in the adult with no manifestations of any rotation in an embryo with similar malformation. Comparing this variation with cases of complete reduplication of the ureter we find the relation of the two segments the same, one ventral to the other, although there is displacement of the ventral ureter in that its orifice lies between that of the dorsal ureter and the Wolffian duct. This crossing of the two ureters is only found at the lower end and does not affect the course of the ureter above. Again in all cases where there is congenital displacement of the kidney and lack of rotation or mal-rotation, the orifice of the ureter is not necessarily affected and in those cases in which the ureter is widely displaced in the female through downgrowth of the Mullerian ducts, the kidney position and ureter course are normal otherwise.
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In the accompanying chart are found curves to represent the wandering of the kidneys; the age in weeks is shown on the right, the size in centimeters on the left, and the number of the embryo plotted below. The uppermost curve is derived from the vertex-breech measurement of the embryos in question, the second and dotted curve the size of the kidney from tip to tip multiplied 10 times, the lowest curve the distance between the two kidneys also multiplied by 10. The kidney does not grow as rapidly as the body up to embryo 32 and then gains on the body size until at 130 mm., the kidney is about 1-lOth the vertex-breech measurement. The distance between the kidneys remains practically the same until 88, then grows apart rapidly (the period of wandering) until 74 is gained when it remains about the same until 224 although the difference between these two embryos, 74 and 224, is 21.0 mm., or in time, about ten days. The kidneys then grow apart even more rapidly than during the period of wandering. This quiescent time I hold to be the stage of vascularization.
 +
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It was stated in an earlier part of this article that the kidney is not vascularized until it has reached its normal height, and that it attains this position in an embryo of about 20.0 mm. This corresponds to the curve. Mr. Eben C. Hill of Johns Hopkins University has also verified this matter in the pig and the fact that the renal artery may sometimes give off the suprarenal and spermatic strengthens the point made.
 +
 +
The idea that the primitive upper and lower sprout of the bud correspond to the upper and lower pelves of the adult kidney is entirely compatible with the findings in the embryo and the adult. My report on the complete doubling of tha ureters in embryos, Mall 173 and Keibel-Piper have confirmed the same in the most important stages in the embryology of this form of anomaly. The form of the pelvis and ureter is undoubtedly dependent on the development of the renal bud while the kidney form is controlled by the mesenchyme.
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I wish in closing to express my indebtedness to Professor Mall for the use of all the numbered embryos and of his model of embryo
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2, to Professor Bardeen for the loan of his models of embryos {{CE163}} and {{CE144}}, to Professor Keibel for embryo Keibel-Piper and to Mr. Hill for data of his findings in the {{pig}}.
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Pohlman AG. A Note on the developmental relations of the kidney and ureter in human embryos. (1905) Johns Hopkins Hospital Bulletin 16: .

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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)

A note on the developmental relations of the kidney and ureter in human embryos

By Augustus G. Pohlman, M. D.,

Assistant Professor of Anatomy, University of Indiana.

Introduction

The first signs of the permanent kidney (metanephros) is found in a dorsal outgrowth of the Wolffian duct close to its orifice in the cloaca. The Wolffian duct (segmental) reaches the caudal part of the enteron in embryo 76 (4.5 mm.). It is of even caliber throughout its course, dilating slightly as it enters the cloaca. As the duct comes into relation with the cloaca, two varieties of epithelium meet, the mesodermic epithelium of the duct and the entodermic of the gut. There must of necessity be an epithelial plate separating the duct from the cloaca, but it probably disappears with its formation.

  • This and other similar figures refer to the catalogue number in the Anatomical Collection of the Johns Hopkins Medical School.


In the slightly older embryo 80 (5.0 mm.) the duct has given off a small shoot which arises dorsally and continues the lumen of the duct into the mesodermic tissue as yet undifferentiated, in which the whole is embedded. The lumen of this bud, the renal bud, is somewhat larger than that of the duct proper and is dilated toward its blind end. The surrounding tissue has become condensed about the end of the bud and is easily recognized by its different arrangement and by its darker stain with carmine. The renal anlage is placed at the second sacral vertebra as nearly as can be estimated, in the uncertainty of the vertebra at this stage and the difficulty in fixing the direction which might be called the right angle to the bent vertebral column. This position does not change until an older stage is reached as was verified in the models of embryo 3 (7.0 mm.) by Professor Mall and embryo 163 (9.0 mm.) by Professor Bardeen.

The renal anlage may be divided into two distinct parts in embryo 2 (7.0 mm.) ; a segment not surrounded by specialized mesodermic tissue, the future ureter, and a segment capped by the specialized tissue, the renal mesenchyme, the kidney and all the derivatives of the bud included within the kidney substance. The two anlages, the right and left, point dorsally from their position on the Wolffian ducts and even converge toward the middle line, and approach each other so closely that it is a matter of 50 microns separating them. The buds are at the same level and the ureter and kidney segments are of equal size.

In embryo 88 (9.0 mm.) the distal end of the bud undergoes a division into an upper and lower sprout which are enclosed in the renal mesenchyme and represent the future upper and lower pelves of the adult kidney. The renal mesenchyme in the meantime has developed in a vertical direction and is bean-shaped. Stationary up to this stage the kidney now begins a rapid wandering to its future permanent position in the body.

The sharp division into an upper and lower sprout is lost in embryo 114 (10.0 mm.). The renal mass is distinctly bean-shaped in reconstruction and rather flattened from side to side. The hilum is situated ventrally. The ureter has elongated but is still in relation with the Wolffian duct dorsally. The kidneys are placed with their upper ends at the brim of the pelvis, the one a little higher than the other. The hilum of the kidney is well marked although the organ is as yet not vascularized. The two kidneys are placed with their long axes parallel and measure from tip to tip about 0.6 mm. and are about 0.2 mm. apart.


The upper border of the developing kidney reaches the third lumbar vertebra in embryo 144 (14.0 mm.). The ureter still emerges from its ventral aspect, but the relations at the lower end have changed. The ureter is rotated to a lateral position on the Wolffian duct and that portion of the duct which lay between the bud and the cloaca has disappeared (?), bringing the orifice of the ureter directly at the cloaca or into the duct at the cloaca. The kidney is without blood supply and lies behind the Wolffian body.

In embryo 43 (16.0 mm.) the kidney lies higher than in the preceding embryo. In addition it has imdergone an axial rotation bringing the hilum to its mesial border, i. e., turned about 90° toward the middle line. The ureter has acquired a distinct orifice into the ventral segment of the cloaca lateral to the orifice of the Wolffian duct. The cloaca is completely divided at this stage.

The kidney arrives at its normal height in embryo 22 (20.0 mm.). The rotation is maintained and the kidneys, except that they lie closely together, are in the adult position. The vascularity is as yet problematic. In the meantime the ureter has lost all connection with the Wolffian duct and has grown into a higher and more lateral location as a fixed structure. The Miillerian ducts in this embryo are unusual in that the left duct has reached the urogenital sinus while the right lies a full slide higher up. The kidneys are about 1.0 mm. apart.


Chronologically: The Wolffian duct joins the cloaca at 4.5 mm.; the renal buds appear at 5.0 mm.; the renal buds may be differentiated into two segments, the ureter and kidney, at 7.0 mm. when they lie opposite the second sacral vertebra ; at 10.0 mm. the upper border of the kidney is at the brim of the pelvis; at 14.0 mm. the ureter lies lateral to the Wolffian duct and the upper pole of the kidney is at the third lumbar vertebra ; at 16.0 mm. the kidney has passed the midlumbar line and has been rotated through 90° on its long axis while the ureter has a separate orifice in the urogenital sinus; at 20.0 mm. the ureter and kidney are in the relative noimal position and the Miillerian ducts have gained the sinus.


The rotation of the kidney and the displacement of the ureter at the lower end, although they occur at the same time, are distinct processes. This may be demonstrated in cases of incomplete double ureter where the ureter is divided into two segments somewhere along its course. The ventral segment proceeds from the upper pelvis of the kidney, while the dorsal branch is connected with the lower pelvis. If there were any connection between the rotation of the kidney at the midlumbar line with the lateral displacement at the lower end of the ureter, there would be evidences of such rotation along the course of the anomalous branches of the ureter, but we find the position of the two segments, the one ventral to the other maintained even in the adult with no manifestations of any rotation in an embryo with similar malformation. Comparing this variation with cases of complete reduplication of the ureter we find the relation of the two segments the same, one ventral to the other, although there is displacement of the ventral ureter in that its orifice lies between that of the dorsal ureter and the Wolffian duct. This crossing of the two ureters is only found at the lower end and does not affect the course of the ureter above. Again in all cases where there is congenital displacement of the kidney and lack of rotation or mal-rotation, the orifice of the ureter is not necessarily affected and in those cases in which the ureter is widely displaced in the female through downgrowth of the Mullerian ducts, the kidney position and ureter course are normal otherwise.


In the accompanying chart are found curves to represent the wandering of the kidneys; the age in weeks is shown on the right, the size in centimeters on the left, and the number of the embryo plotted below. The uppermost curve is derived from the vertex-breech measurement of the embryos in question, the second and dotted curve the size of the kidney from tip to tip multiplied 10 times, the lowest curve the distance between the two kidneys also multiplied by 10. The kidney does not grow as rapidly as the body up to embryo 32 and then gains on the body size until at 130 mm., the kidney is about 1-lOth the vertex-breech measurement. The distance between the kidneys remains practically the same until 88, then grows apart rapidly (the period of wandering) until 74 is gained when it remains about the same until 224 although the difference between these two embryos, 74 and 224, is 21.0 mm., or in time, about ten days. The kidneys then grow apart even more rapidly than during the period of wandering. This quiescent time I hold to be the stage of vascularization.


It was stated in an earlier part of this article that the kidney is not vascularized until it has reached its normal height, and that it attains this position in an embryo of about 20.0 mm. This corresponds to the curve. Mr. Eben C. Hill of Johns Hopkins University has also verified this matter in the pig and the fact that the renal artery may sometimes give off the suprarenal and spermatic strengthens the point made.

The idea that the primitive upper and lower sprout of the bud correspond to the upper and lower pelves of the adult kidney is entirely compatible with the findings in the embryo and the adult. My report on the complete doubling of tha ureters in embryos, Mall 173 and Keibel-Piper have confirmed the same in the most important stages in the embryology of this form of anomaly. The form of the pelvis and ureter is undoubtedly dependent on the development of the renal bud while the kidney form is controlled by the mesenchyme.


I wish in closing to express my indebtedness to Professor Mall for the use of all the numbered embryos and of his model of embryo 2, to Professor Bardeen for the loan of his models of embryos 163 and 144, to Professor Keibel for embryo Keibel-Piper and to Mr. Hill for data of his findings in the pig.


Cite this page: Hill, M.A. (2020, March 29) Embryology Paper - A note on the developmental relations of the kidney and ureter in human embryos (1905). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_A_note_on_the_developmental_relations_of_the_kidney_and_ureter_in_human_embryos_(1905)

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