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Pohlman AG. [[Paper - Double ureters in human and pig embryos|Double ureters in human and pig embryos]]. (1919) Anat. Rec. 

369-


Double Ureters In Human And Pig Embryos

A. G. Pohlman

Department of Anatomy, St. Louis University

THREE fiGURES


The double ureter has a certain developmental importance in
that it furnishes a clew for the disappearance‘ of the cloacal
segment of the Wolffian duct, and its manner of incorporation
into the bladder. Two cases of complete double ureter were
reported in 1905 ;1 one is the Mall embryo, no. 175 (13 mm.)
and the other in the Keibel embryo, Piper (24 mm.). Both of
these embryos show that the ureter from the lower part of the
kidney lies dorsal to the ureter from the upper pole, and as they
swing around to occupy a lateral position on the Wolffian duct,
the dorsal or lower ureter is displaced lateralward, while the
ventral or upper ureter lies between it and the Wolffian duct.
This rotation from a dorsal position on the Wolffian duct to a
lateral one is completed at the time when the cloacal segment of
the duct has expanded into the lateral funnel-shaped process of
the bladder proper. The accompanying figures, nos. 27 to 24,
inclusive, and‘ 22 and 19, are taken from drawings made of the
Keibel embryo, which is at present not available for study.
figure 27, the lowest of the series, shows the. convexity of the
right ureter A, and 26, the section immediately above it, shows
the opening of this ureter into the bladder. The next section
up indicates the convexity of ureter B, indicated in black, and
section 24 its orifice in the bladder. In figure 22, ureter B
lies slightly dorsolateral to ureter A, and the convexity of the
curve of the left ureter is shown with its orifice in the bladder

1 Abnormalities in the form of the kidney and ureter dependent on the development of the renal bud. A. G. Pohlman, Johns Hopkins Hospital Bull., vol.
16, Feb., 1905.


three sections higher up (19). This latter figure shows the
double ureter on the right lying almost in the sagittal plane,
i.e., the ureter B from the lower pole of the kidney practically
dorsal to ureter A from the upper pole. Both of these ureters
have already migrated to a position cephalad to the opening of
the Wolffian duct, and the interval between the orifices is so
small that in a gross specimen they might readily be mistaken
for a single orifice.


In the Mall embryo the orifices of the two ureters and the
Wolffian duct are, so far as I was able to determine them, in
common. It would seem, therefore, that where we have wide
displacements of the orifices of the two ureters they are to be found in displacement downward of the median one, i.e., the one
lying between the normal ureter orifice and the opening of the
Wolffian duct.

I also called attention to the fact that the rotation of the
ureter around the Wolffian duct was entirely independent of
kidney rotation and position; and that the displacement of the
ureter was completed at the time that the cloacal segment of
the Wolffian duct was definitely incorporated into the bladder.
In the pig the rotation seems to be accomplished before this
absorption is completed, so that the ureter opens laterally into
the Wolffian duct at some distance from the orifices of the duct
into the urogenital sinus. '


I have found but two pigs with evident ureteral duplication or
diverticulae. Pig 47 has a complete double ureter on the left
side. figure 9-24 shows the emergence of the upper ureter from
the pelvis of the kidney. figure 10-5 shows that of the lower
ureter from its pelvis. In 11-1 the ureter from the lower pelvis
B is already lateral to ureter A from the upper pelvis, and maintains this position through 11-2, 11-3, and 11-4. In 11-3 the
two ureters open into the lateral expansion of the Wolffian duct
in about a normal position as indicated in the normal ureter on
the right; ureter B lying in front of ureter A.

 

The only essential difference between the relations as shown in
fig. 47 and the human embryo is that the twist of the two ureters
in the pig appears to run to a higher level than in the human
being, and, second, that a cloacal segment of the Wolffian duct
persists in the pig at the time that the rotation has been
completed.

Cases have been reported in the human being, however, where
this general rule, that the ureter from the upper pelvis comes to
lie medial to the ureter from the lower pelvis and in consequence
has a lower orifice in the bladder, does not obtain. Weigert,



Hyrtl and Kerr” have reported cases in which the rule above
stated has not prevailed. Kerr has made a report on a case of a
double ureter in which the ureter from the upper pelvis lies
lateral to the ureter from the lower pelvis as the two curve
toward the bladder. In so far as I am aware, there is no developmental explanation. for this anomaly, however, a somewhat
similar condition was found in pig 3. figure 10-8 shows the
origin of the right ureter from the kidney. figure 10-15 shows
the lower pole of this kidney with the two ureters, right and left, running forward. In figure 10-17 shows the right ureter A,
and behind it a blind ending ureteral diverticulum indicated in
black and marked RX. Following this down 10-20 shows‘ it
somewhat more medial than in 17, and in 10:23 and 10-24 this
lower dorsal ureteral diverticulum comes to occupy the position
of the normal ureter from the upper pelvis of the kidney. It
appears to end blindly or to fuse with the right ureter in 10-22.
Unfortunately, this pig series was cut at 50,; and the finer details
of structure cannot be definitely determined.

5 Complete double ureter in man by A. T. Kerr, Anatomical Record, vol. 5,
1911, p. 55.




It would, however, appear possible that this diverticulum to
form a second ureter might have arisen from the first ureter but
close to its orifice in the Wolffian duct, and on its medio—inferior
aspect, and that it was merely dragged out in the upward migration of the kidney. However, had this aberrant ureter connected functionally with the kidney proper, it would have taken
exactly the position described in these cases which appear contrary to the rule, and would also mean that Where the ureter
from the lower part of the kidney comes to lie medial to the
ureter from the upper part of the kidney, that the two orifices
into the bladder are close together, in other words, we would
not expect a displacement of the medial orifice away from a
normal position. ' i

This would, therefore, merely be an exaggeration of an incompletely double ureter, and it would only differ from the latter
by reason of the origin of the lower ureter close to the orifice of
the upper ureter in the Wolffian duct. It would, of course, be
possible to establish this point quite definitely if sufficient number of ureteral duplications could be observed in serial sections.
The anomaly is so unusual that the chance of finding intermediate stages, even in the analysis of large numbers of series,
is very slight.

I am merely reporting this anomaly because it is so unusual
and because it seems to offer some sort of explanation for the few
cases of complete ureter duplication which do not follow the rule.


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