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Immature glomeruli in cot death kidneys
Forensic Science International,
20 (1982)
IMMATURE
GLOMERULI
J. HIRVONEN,
H. AUTIO-HARMAINEN
Departments
of Forensic
117 - 120
IN COT DEATH
Medicine
117
KIDNEYS
and 0. NYBLOM
and Pathology,
University
of Oulu,
Oulu (Finland)
(Received October 22, 1981; accepted December 18, 1981)
Summary A morphometric study on the kidneys of cot death cases and age-matched controls was carried out using a point-counting method. The average proportions of the various kidney structures, especially the percentage of foetal glomeruli, were similar in both groups. This percentage decreased after the age of six months. The hypothesis that cot death may be caused by renal insufficiency associated with immaturity of glomeruli gained no morphological or morphometric support.
Introduction A couple of years ago it was reported that in cot death cases the kidneys are less mature than in other infants at that age, and that the number of foetal-type glomeruli should be greater in sudden infant death syndrome [l] . The hypothesis for explaining the death was that due to the immaturity of the kidneys electrolyte imbalances would easily develop, e.g. during mild infection. The mechanism of death could thus be cardiac dysfunction. This approach seemed attractive since dehydration with high cerebrospinal fluid urea has been suggested as a significant factor in sudden infant death (SID) [ 21. We therefore decided to study this hypothesis in our material of cot deaths by investigating the kidneys morphometrically using age-matched reference material.
Material and methods The material consisted of 14 cot deaths and 13 age-matched controls, all from 1 to 9 months of age. These included 8 cot deaths and 7 controls at the age of 0 - 3 months, 4 cot deaths and 4 controls at 3; - 6 months and 2 cot deaths and 2 controls more than 6 months old. The oldest infant was 9 months old. The main causes of death among the controls were infections, congenital disease, traumatic lesion or hemorrhagia. No renal or cardiac diseases were included. Qualitative and quantitative microscopic analysis was carried out on random longitudinally cut pieces of kidney, 1.5 X 1.5 cm, all fixed in 10% 0379-0738/82/0000-0000/$02.?5
@ Elsevier Sequoia/Printed
in The Netherlands
Fig. 1. An immature glomerulus from Peripheral capillary loops are covered Haematoxylin-eosin, x 1600.
the subcapsular cortex of a 2 l/2-month by a rim of densely packed epithelial
SID case. cell nuclei.
formalin and embedded in paraffin. Tissue sections of thickness 4 Mm were stained with haematoxylin and eosin. Only one section per case was analysed morphometrically. The point-counting method was used for determination of the volume fraction (i.e. volume densities) of the renal cortex (V, cortex) using a transparent multipurpose test grid of 42 points [ 31 with a test line length of 0.4 cm placed on the section. The medulla-cortex border was marked on the section before measuring. Cortical parameters including the volume fractions of mature (Vvo) and immature (VvImmo ) glomeruli, numerical density of glomeruli (Nvo) and the volume fraction of the tubules and interstitium (Vv, + & were measured using a Leitz Mikro Promar microprojector. The tissue sections were projected onto a table and counted using a transparent multipurpose test screen of 100 points placed on the tissue image. Counting was started from the left subcapsular corner of the section and proceeded to the juxtamedullary area of the cortex. This was continued in a zig-zag pattern through the whole preparation. Vvo, Nvo and Vv,,,, were measured at a total magnification of X 60. Each point falling on a glomerular tuft and each glomerular section with more than one half of the profile inside the test square was recorded. The standard error of the mean was 15% or less for each case analysed. The volume fraction of immature glomeruli was analysed at a total magnification
119 TABLE Results
1 of the measurements
of cortical
parameters
Controls
SIDs
vv cortex (%) V,, vVt
(s) + int (%)
VVImmG
@)
Nv~/mm
3
o-3 n=8
31-6 .24
6 (months) II=2
o-3 II=7
31 .34
66.0 f 12.0
65.0 ? 10.0
58.0 ? 2.0
72.0 ?: 14.0
62.0 f 17.0
5.3 f 0.9
5.2 ? 0.9
5.5 f 1.6
5.8 i 1.4
4.8 t 1.5
4.9 r 0.5
94.8 f 1.1
94.7 + 0.9
95.0 t 1.4
94.5 2 1.4
95.2 f 1.7
95.5 f 0.7
19.9 t 10.0 144.1
t 44.5
21.0 t 6.0* 120.2
k 31.3
6.5 f 7.0* 98.6 t 23.3
18.0 f 6.0** 194.0
+ 66.7*
-6
20.0 t 11.0 165.0
* 33.5*
6 (months) n=2 42.0 ? 21.0
5.5 f 2.0** 78.1 f 37.6**
* p < 0.05. ** p < 0.01. V v co*x
= volume fraction of cortex, = volume fraction of glomeruli in the cortex, of tubules and interstitium, vVt + int = volume fraction = volume fraction of immature glomeruli within total glomeruli, VVimmG = number of glomeruli per unit volume of cortex. NVG VW
of X 250. Ten consecutive fields per case including 5 subcapsular and 5 juxtamedullar regions were analysed. A glomerulus was regarded as immature when more than 2/3 of the peripheral capillary loops were lined with densely packed epithelial cells (Fig. 1). The formulae developed by Weibel et al. [4] were used for the calculation of volume and numerical densities. The statistical analyses were performed using Student’s t-test.
Results The overall architecture of the renal cortex and medulla was similar in the cot deaths and controls. The results of the morphometric analysis are given in Table 1. There were no significant differences in the four parameters between the groups investigated. The proportion of immature glomeruli was about three times higher below the age of six months than above it in both the cot deaths and the controls and the number of glomeruli per unit volume of cortex (NVG) declined gradually with advancing age.
Discussion The analysis showed a normal maturation of the kidneys and glomeruli in cot deaths and age-matched controls. Similarly, no difference in the proportion of morphologically immature glomeruli was observed. Thus the
120
results do not support the findings of Suzuki et al. [l] concerning the increased number of foetal glomeruli in cot deaths, but were consistent with the report of Andrews [2] who found no abnormalities in the kidneys of SID infants with high cerebrospinal urea values. If the mechanism of death involves electrolyte disturbances, the cause of these probably lies elsewhere, perhaps in an inadequate intake of water. The highest proportion of immature glomeruli, observed in the infants under the age of 6 months, was one fifth in both the cot deaths and the controls. So that the number of mature glomeruli would still leave a basis for good functional capacity at this age. The decrease in the numerical density of glomeruli with advancing age reflects the changes in glomerular size and tubular length which are known to occur after the neonatal period [ 51. The real number of glomeruli actually remain unchanged from birth to middle age [6]. This fact is not contradicted by the present results.
References 1 T. Suzuki, S. Kashimura and K. Umetsu, Sudden infant death syndrome: histological studies on adrenal gland and kidney. Forensic Sci. hf., 15 (1980) 41. 2 P. S. Andrews, Cot deaths and malnutrition: the role of dehydration. Med. Sci. Law, 15 (1975) 47. 3 E. R. Weibel, G. S. Kistler and W. F. Scherle, Practical stereological methods for 23. morphometric cytology. J. Cell Biol., 30 (1966) 4 E. R. Weibel, W. Staubli, H. R. Gnlgi and F. A. Hess, Correlated morphometric and biochemical studies on the liver cell. I. Morphometric model, stereologic methods and normal morphometric data for rat liver. J. Cell Biol., 42 (1969) 68. 5 G. H. Fetterman, N. A. Shuplock, F. J. Philipp and H. S. Gregg, The growth and maturation of human glomeruli and proximal convolutions from term to adulthood. Pediatrics, 35 (1965) 601. 6 M. S. Dunnill and W. Halley, Some observations on the quantitative anatomy of the 113. kidney. J. Pafhol., 110 (1973)
20 (1982)
IMMATURE
GLOMERULI
J. HIRVONEN,
H. AUTIO-HARMAINEN
Departments
of Forensic
117 - 120
IN COT DEATH
Medicine
117
KIDNEYS
and 0. NYBLOM
and Pathology,
University
of Oulu,
Oulu (Finland)
(Received October 22, 1981; accepted December 18, 1981)
Summary A morphometric study on the kidneys of cot death cases and age-matched controls was carried out using a point-counting method. The average proportions of the various kidney structures, especially the percentage of foetal glomeruli, were similar in both groups. This percentage decreased after the age of six months. The hypothesis that cot death may be caused by renal insufficiency associated with immaturity of glomeruli gained no morphological or morphometric support.
Introduction A couple of years ago it was reported that in cot death cases the kidneys are less mature than in other infants at that age, and that the number of foetal-type glomeruli should be greater in sudden infant death syndrome [l] . The hypothesis for explaining the death was that due to the immaturity of the kidneys electrolyte imbalances would easily develop, e.g. during mild infection. The mechanism of death could thus be cardiac dysfunction. This approach seemed attractive since dehydration with high cerebrospinal fluid urea has been suggested as a significant factor in sudden infant death (SID) [ 21. We therefore decided to study this hypothesis in our material of cot deaths by investigating the kidneys morphometrically using age-matched reference material.
Material and methods The material consisted of 14 cot deaths and 13 age-matched controls, all from 1 to 9 months of age. These included 8 cot deaths and 7 controls at the age of 0 - 3 months, 4 cot deaths and 4 controls at 3; - 6 months and 2 cot deaths and 2 controls more than 6 months old. The oldest infant was 9 months old. The main causes of death among the controls were infections, congenital disease, traumatic lesion or hemorrhagia. No renal or cardiac diseases were included. Qualitative and quantitative microscopic analysis was carried out on random longitudinally cut pieces of kidney, 1.5 X 1.5 cm, all fixed in 10% 0379-0738/82/0000-0000/$02.?5
@ Elsevier Sequoia/Printed
in The Netherlands
Fig. 1. An immature glomerulus from Peripheral capillary loops are covered Haematoxylin-eosin, x 1600.
the subcapsular cortex of a 2 l/2-month by a rim of densely packed epithelial
SID case. cell nuclei.
formalin and embedded in paraffin. Tissue sections of thickness 4 Mm were stained with haematoxylin and eosin. Only one section per case was analysed morphometrically. The point-counting method was used for determination of the volume fraction (i.e. volume densities) of the renal cortex (V, cortex) using a transparent multipurpose test grid of 42 points [ 31 with a test line length of 0.4 cm placed on the section. The medulla-cortex border was marked on the section before measuring. Cortical parameters including the volume fractions of mature (Vvo) and immature (VvImmo ) glomeruli, numerical density of glomeruli (Nvo) and the volume fraction of the tubules and interstitium (Vv, + & were measured using a Leitz Mikro Promar microprojector. The tissue sections were projected onto a table and counted using a transparent multipurpose test screen of 100 points placed on the tissue image. Counting was started from the left subcapsular corner of the section and proceeded to the juxtamedullary area of the cortex. This was continued in a zig-zag pattern through the whole preparation. Vvo, Nvo and Vv,,,, were measured at a total magnification of X 60. Each point falling on a glomerular tuft and each glomerular section with more than one half of the profile inside the test square was recorded. The standard error of the mean was 15% or less for each case analysed. The volume fraction of immature glomeruli was analysed at a total magnification
119 TABLE Results
1 of the measurements
of cortical
parameters
Controls
SIDs
vv cortex (%) V,, vVt
(s) + int (%)
VVImmG
@)
Nv~/mm
3
o-3 n=8
31-6 .24
6 (months) II=2
o-3 II=7
31 .34
66.0 f 12.0
65.0 ? 10.0
58.0 ? 2.0
72.0 ?: 14.0
62.0 f 17.0
5.3 f 0.9
5.2 ? 0.9
5.5 f 1.6
5.8 i 1.4
4.8 t 1.5
4.9 r 0.5
94.8 f 1.1
94.7 + 0.9
95.0 t 1.4
94.5 2 1.4
95.2 f 1.7
95.5 f 0.7
19.9 t 10.0 144.1
t 44.5
21.0 t 6.0* 120.2
k 31.3
6.5 f 7.0* 98.6 t 23.3
18.0 f 6.0** 194.0
+ 66.7*
-6
20.0 t 11.0 165.0
* 33.5*
6 (months) n=2 42.0 ? 21.0
5.5 f 2.0** 78.1 f 37.6**
* p < 0.05. ** p < 0.01. V v co*x
= volume fraction of cortex, = volume fraction of glomeruli in the cortex, of tubules and interstitium, vVt + int = volume fraction = volume fraction of immature glomeruli within total glomeruli, VVimmG = number of glomeruli per unit volume of cortex. NVG VW
of X 250. Ten consecutive fields per case including 5 subcapsular and 5 juxtamedullar regions were analysed. A glomerulus was regarded as immature when more than 2/3 of the peripheral capillary loops were lined with densely packed epithelial cells (Fig. 1). The formulae developed by Weibel et al. [4] were used for the calculation of volume and numerical densities. The statistical analyses were performed using Student’s t-test.
Results The overall architecture of the renal cortex and medulla was similar in the cot deaths and controls. The results of the morphometric analysis are given in Table 1. There were no significant differences in the four parameters between the groups investigated. The proportion of immature glomeruli was about three times higher below the age of six months than above it in both the cot deaths and the controls and the number of glomeruli per unit volume of cortex (NVG) declined gradually with advancing age.
Discussion The analysis showed a normal maturation of the kidneys and glomeruli in cot deaths and age-matched controls. Similarly, no difference in the proportion of morphologically immature glomeruli was observed. Thus the
120
results do not support the findings of Suzuki et al. [l] concerning the increased number of foetal glomeruli in cot deaths, but were consistent with the report of Andrews [2] who found no abnormalities in the kidneys of SID infants with high cerebrospinal urea values. If the mechanism of death involves electrolyte disturbances, the cause of these probably lies elsewhere, perhaps in an inadequate intake of water. The highest proportion of immature glomeruli, observed in the infants under the age of 6 months, was one fifth in both the cot deaths and the controls. So that the number of mature glomeruli would still leave a basis for good functional capacity at this age. The decrease in the numerical density of glomeruli with advancing age reflects the changes in glomerular size and tubular length which are known to occur after the neonatal period [ 51. The real number of glomeruli actually remain unchanged from birth to middle age [6]. This fact is not contradicted by the present results.
References 1 T. Suzuki, S. Kashimura and K. Umetsu, Sudden infant death syndrome: histological studies on adrenal gland and kidney. Forensic Sci. hf., 15 (1980) 41. 2 P. S. Andrews, Cot deaths and malnutrition: the role of dehydration. Med. Sci. Law, 15 (1975) 47. 3 E. R. Weibel, G. S. Kistler and W. F. Scherle, Practical stereological methods for 23. morphometric cytology. J. Cell Biol., 30 (1966) 4 E. R. Weibel, W. Staubli, H. R. Gnlgi and F. A. Hess, Correlated morphometric and biochemical studies on the liver cell. I. Morphometric model, stereologic methods and normal morphometric data for rat liver. J. Cell Biol., 42 (1969) 68. 5 G. H. Fetterman, N. A. Shuplock, F. J. Philipp and H. S. Gregg, The growth and maturation of human glomeruli and proximal convolutions from term to adulthood. Pediatrics, 35 (1965) 601. 6 M. S. Dunnill and W. Halley, Some observations on the quantitative anatomy of the 113. kidney. J. Pafhol., 110 (1973)