The American Journal of Medical Sciences and Pharmaceutical Research
51
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TYPE
Original Research
PAGE NO.
51-55
10.37547/tajmspr/Volume07Issue04-09
OPEN ACCESS
SUBMITED
28 February 2025
ACCEPTED
29 March 2025
PUBLISHED
30 April 2025
VOLUME
Vol.07 Issue 04 2025
CITATION
A.A. Nasirov. (2025). Histomorphological changes in the wall of the
pyeloureteral segment in young children. The American Journal of Medical
Sciences and Pharmaceutical Research, 7(04), 51
–
55.
https://doi.org/10.37547/tajmspr/Volume07Issue04-09
COPYRIGHT
© 2025 Original content from this work may be used under the terms
of the creative commons attributes 4.0 License.
Histomorphological
changes in the wall of the
pyeloureteral segment in
young children
A.A. Nasirov
Tashkent Paediatric Medical Institute, Uzbekistan
Abstract:
Purpose of the study
. To study histo-
morphological changes in the wall of the pyeloureteral
segment in infants early age.
Materials and Methods
. The data of the results of
comprehensive examination and surgical treatment of
children aged from 1 month to 3 years who were treated
in the urology department of the clinic of the Tashkent
Pediatric Medical Institute (Tashkent Pediatric Medical
Institute) and in the Training and Methodological Centre
of Neonatal Surgery at the Republican Perinatal Centre
(RPC) from 2014 to 2022 served as the material for the
study. A retrospective and prospective analysis of
clinical materials concerning the diagnosis and
treatment of 131 children was performed. Among the
patients, right-sided hydronephrosis was detected in 49
(37.4%) patients, left-sided obstruction in 73(55.7%)
children, and 9 (6.9%) cases had bilateral lesions.
Results
. When analysing the characteristics of ureteral
structural changes in age groups, it was found that in the
group of children older than 1 year of age, the number
of reversible and irreversible structural abnormalities
did not differ significantly. In the age group of children
under 1 year of age, the differences in the frequency of
reversible and irreversible ureteral structural changes
were statistically significant.
Keywords:
Hydronephrosis, children, pyeloureteral
segment.
Introduction:
Malformations of the genitourinary
organs account for 15-45% of all ano- genital
malformations of embryonic development. In this case,
hydronephrosis due to obstruction of the pyeloureteral
segment (PUS) obstruction is the most frequent cause
of plastic surgery on the upper urinary tract in children.
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According to the literature, the prevalence of PUS
obstruction ranges from 2-6 cases per 1000 newborns
[1,2,14,18]. According to retrospective studies,
antenatal detection of upper urinary tract dilatation is
1:500, but the actual number of surgeries for PUS
obstruction remains relatively at the level of 1:1250-
1500 live births [8,16,17]. Analysis of the data on
morphological abnormalities in the PUS area in
hydronephrosis shows that dysplastic changes in the
smooth muscle structures of the ureter wall, excessive
collagen accumulation in the intermuscular spaces,
depletion of innervation in the PUS area, increased
leiomyocyte apoptosis, impaired differentiation of the
uroepithelium, and various changes in the extracellular
matrix are accurately established. However, to date,
there is no consensus on the etiology and pathogenesis
of morphological changes in the PUS [14,16,17]. In the
available literature, there are few studies on the
normal morphological picture of the pelvis and ureteric
duct in children under one year of age [4,12,14] and in
adults (over 18 years of age) [3,7,15].
However, the results of most studies do not
characterise in detail the structural changes at the
early stages of postnatal ontogenesis and are mainly
devoted to, predicting the results of plastic surgeries
for obstruction of the pyelo-ureteral segment
[9,10,11,18]. Thus, the lack of unified criteria for the
indication for one or another type of treatment of
congenital hydronephrosis in infants is the reason for
contradictory and hardly comparable data.
Purpose of the study
was to investigate
histomorphological changes in the wall of the
pyeloureteral segment in young children.
METHODS
The material for the study was the data of the results
of comprehensive examination and surgical treatment
of 131 children aged from 1 month to 3 years who were
under treatment from 2014 to 2022.
Among the patients, right-sided hydronephrosis was
detected in 49 (37.4%) patients, and left-sided
obstruction in 73 (37.4%) patients.
left-sided obstruction in 73 (55.7%) children, and 9
(6.9%) cases had bilateral lesions.
lesion. The age of the operated patients ranged from 1
month to 3 years and averaged 10.06±0.3 months. In
the distribution of patients by sex, there was a
predominance of boys - 100 (76.3%), compared to girls
- 31 (23%), both in the total sample and in each age
group separately.
Patients older than 3 months were hospitalised at the
TashPMI clinic, where the whole spectrum of
radiourological
examination,
including
ultrasonography, excretory urography, micturition
cystography, multispiral computed tomography, and
clinical and laboratory investigations.
For radioisotope renoscintigraphy, children were
referred to the nuclear medicine department of the
Republican Specialised Nuclear Medicine Department of
the Republican Specialised Scientific and Practical
Medical Centre of Endocrinology.
Due to the routine use of ultrasound screening of
pregnant women, 71 (54%) fetuses had renal cavity
dilation detected antenatally at 26 to 32 weeks
gestational age.
All patients underwent a comprehensive examination,
which included clinical and laboratory diagnostic
methods, radiology, and radiotherapy, laboratory
diagnostic
methods,
radiation,
radioisotope,
morphological
and
histological
methods
of
investigation.
In determining the severity of obstruction of the pyelo-
urethral segment (PUS), we used the classification
proposed by the Society for Foetal Urology, according to
which five degrees of congenital hydronephrosis are
distinguished. In this case, the 0 degree - unchanged
collecting system of the kidney, the 1 degree - moderate
enlargement of the central renal complex, the 2 degree
- enlargement of the lobule without calicoectasia, the 3
degree - enlargement of the whole PUS without
parenchyma atrophy and the 4 degree - significant
enlargement of the PUS with renal parenchyma
atrophy.
Pathomorphological study of biopsy specimens of the
pelvic wall and pelvic-ureteric segment was carried out
for the purpose of pathomorphological examination
was performed to study the structural changes of the
affected parts of the upper urinary tract. The ureter with
the area of narrowing was additionally dissected
longitudinally to study tissue relationships and to
determine the degree of deformation. The material was
then washed in running water (24 hours), dehydrated in
alcohols of increasing concentration (50o to 100o), and
embedded in paraffin. Sections 5-6 µm thick were made
on a sledge microtome.
Ultrastructural elements of muscle and connective
tissue of biopsy specimens were studied by electron
microscopy. General dysplastic and structural changes
of the resected part of the pelvis and the ureteral lobule
were analysed. The morphological study was carried out
in two stages. At the first stage, the whole thickness of
the biopsy specimen, each of the constituent layers
(mucosa with submucosa, muscular) was analysed on
the basis of sections stained with hematoxylin and eosin
of the deformed part of the ureter. At the second stage,
the volume ratio of connective and muscular tissues was
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The American Journal of Medical Sciences and Pharmaceutical Research
determined on the slices stained according to the Van-
Gizon method. Van-Gizon staining is widely used,
because it gives unequal staining of different tissues
and allows to distinguish smooth muscle tissue from
connective tissue in the studied pyeloureteral
segment.
RESULTS AND DISCUSSION
The structural and functional state of the upper urinary
tract under normal conditions is characterised by the
following features: the epithelium lining it is
multilayered. Cubic shaped cells are located on the
well-defined basal membrane, the following 3-4 layers
are formed by cells of different shapes - rounded cells
of different shapes - rounded, oval, spindle-shaped. On
the surface of the urinary tract they are flattened and
elongated. Under the epithelium there is loose
connective tissue with moderate amount of blood
capillaries. Fibroblasts and fibrocytes are single, may
be detected near the basal membrane along the
epithelium. Collagen and elastic fibres are arranged
without a definite orientation. The muscular sheath
consists of two layers: a longitudinal oblique layer and
an outer circular layer. It is characteristic that in the
pyelourethral section, bundles of smooth muscle fibres
and cells are accompanied by a large number of nerve
fibres, which form numerous plaques on the surface of
the cells.
of the cells. Between the bundles of smooth muscle
cells, the connective tissue layers are thin, contain
blood and blood vessels are thin and contain blood
capillaries forming a network-like framework. Large
bundles of smooth muscle cells around have a more
pronounced connective tissue sheath, where arteries
are revealed. sheath, where arterial vessels of larger
diameter are identified. The outer adventitial sheath is
rich in vessels of different calibre and type, contains
many alipocytes, adventitial and other connective tissue
cells.
On morphological examination in the area of narrowing
of the pyeloureteral segment the structure is
polymorphic. It should be noted that all layers of the
ureter are involved in the process. At the same time,
various degrees of PUS structure disorders are detected,
from urothelium hypertrophy to total overgrowth of
connective tissue. Along with this, in some cases,
predominance of intermuscular tissue layers with
epithelium hypertrophy can be noted. In some cases,
epithelium and muscle layer may be absent, then a
sclerosed area consisting of thickened dense connective
tissue with coarse bundles of collagen fibres oriented
longitudinally near the lumen, and deeper - in different
directions is revealed.
The results of morphological studies performed in 33
children under 3 years of age with ureteral stenosis are
presented in Table 1.
Histomorphological 10 changes in the PUS wall in
children with ureteral stenosis
In some cases, the epithelium and muscle layer may be
absent, then a sclerosed area consisting of thickened
dense connective tissue with coarse bundles of collagen
fibres oriented longitudinally near the lumen, and
deeper in different directions is revealed.Morphological
studies performed in 33 children under 3 years of age
with ureteral stenosis showed the following spectrum of
changes in its structure and are presented in Table 1.
Table 1
Histomorphological 10 changes in the PUS wall in children with ureteral stenosis
ureter
Age
Myocyte hypertrophy,
hypertrophy of mucosa
Total
fibrosis
Up to 1 year (n=19)
16
3
Up to 3 years (n=14)
9 5
9
5
Total
25
8
Hypertrophy of muscle fibres with thickening of the
mucosal layer was found in 14 cases
(Fig. 1) and in 11 biopsy specimens the cause of
obstruction was hypertrophy of urothelium, reducing
the the ureteral lumen. Diffuse increase of collagen
fibres was found in 8 ureters (Figure 2).
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Total number of ureters with preserved structure
(hypertrophy of myocytes or mucosa).
myocytes or mucosa - 25 ureters) significantly
exceeded the number of ureters with deep destructive
changes of all layers - 8 ureters. The frequency of PUS
obstruction as a result of tissue changes, which may
well be reversible, was significantly higher than the
frequency of structural disorders, which were
irreversible in nature (Table 2).
Figure 1. Hypertrophy of myocytes. Colouring
haematoxylin and eosin, magnification 100
Fig. 2. Diffuse distribution connective tissue with
reduction number of myocytes.
Van-Gizon, magnification 400.
.
Table 2
Differences between the frequencies of tissue pathology in the group of children
depending on age
Indicators
Category
n
Observed
frequencies
Verifiable
frequencies
p
Fibrosis
1
8
0,25
Not fibrosis
0
25
0,75
0,5
0,014
Older than1 year
Fibrosis
0
5
0,35
0,50
0,7
Not fibrosis
1
9
0,64
До 1 года
Fibrosis
0
3
0,15
0,50
0,007
Not fibrosis
1
16
0,85
CONCLUSION
Thus, when analysing the characteristics of structural
changes of the ureter in age groups, it was found that
in the group of children older than 1 year of age, the
number of reversible and irreversible structural
abnormalities did not differ significantly. In the age
group of children under one year of age, the
differences in the frequency of reversible and
irreversible
ureteral structural
changes
were
statistically significant.
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