scholarly journals GLOMERULAR NUMBER AND CAPILLARY DIMENSIONS IN THE NORMAL LAMB KIDNEY

2011 ◽  
Vol 21 (3) ◽  
pp. 157 ◽  
Author(s):  
Julian Brown ◽  
Todd A Briscoe ◽  
Richard Harding ◽  
Megan L Cock ◽  
John F Bertram ◽  
...  
Keyword(s):  
Surface Area ◽  
Later Life ◽  
Renal Pathology ◽  
Renal Development ◽  
Nephron Number ◽  
Capillary Surface ◽  
Capillary Length ◽  
Nephron Endowment ◽  
Physical Disector ◽  
Filtration Surface

Reduced nephron endowment, either inherited or acquired, has been linked to adult renal pathology as well as hypertension. The sheep provides an excellent model for studying nephrogenesis and renal development because, as in humans, nephrogenesis is complete before birth. In the present study, the physical disector/fractionator method was used to estimate the total number of glomeruli, and thereby nephrons, in normal lambs. Glomerular capillary parameters including mean capillary length per glomerulus, mean capillary surface area per glomerulus and total renal filtration surface area (TRFSA) were also estimated. Total glomerular, and hence nephron number was 333,832 ± 69,560 (mean± standard deviation). TRFSA was 10.95 ± 3.64 x 104 mm2• These results establish a methodology for future investigations, using the sheep as a model, into the effects of depleted nephrogenesis on renal pathology in later life.

Muscle capillary-to-fiber perimeter ratio: morphometry

1991 ◽  
Vol 261 (5) ◽  
pp. H1617-H1625 ◽  
Author(s):  
O. Mathieu-Costello ◽  
C. G. Ellis ◽  
R. F. Potter ◽  
I. C. MacDonald ◽  
A. C. Groom
Keyword(s):  
Surface Area ◽  
Muscle Fiber ◽  
Sarcomere Length ◽  
Fiber Surface ◽  
Capillary Surface ◽  
Capillary Length ◽  
Hindlimb Muscles ◽  
Using Data ◽  
Degree Of Extension

It is known that a substantial amount of capillary tortuosity is found in shortened muscles. However, the increased capillary length and surface area contributed by tortuosity and branching are seldom taken into account when capillarity is estimated and/or blood-tissue exchange is modeled in muscles. In this paper, we sought morphometric estimates of capillarity in transverse sections that incorporated data on capillary geometry. We derived equations to estimate capillary perimeter per fiber perimeter (i.e., capillary-to-fiber perimeter ratio) in transverse sections. We show how capillary-to-fiber perimeter ratio is related to capillary surface per fiber surface, i.e., to the amount of capillary surface available for exchange per muscle fiber surface area, and how it can be obtained by morphometry. Because capillary tortuosity and fiber perimeter are both a function of sarcomere length, the degree of extension or shortening of muscle samples obviously needs to be taken into account when capillary-to-fiber perimeter ratio is compared between muscles and/or samples. Using data currently available on capillary length and diameter with fiber shortening and extension, we show that it is a feature of capillary-to-fiber perimeter ratio to change relatively little with sarcomere length. As sarcomere length decreases from 2.80 to 1.58 microns in perfusion-fixed hindlimb muscles of rats, capillary and fiber perimeters in transverse sections increase substantially, whereas the ratio between the two variables, capillary-to-fiber perimeter ratio, changes only less than or equal to 10-15%.(ABSTRACT TRUNCATED AT 250 WORDS)

Rat Utricular Macula: Blood Flow and Stereological Assessment of Capillary Morphology

1993 ◽  
Vol 102 (11) ◽  
pp. 893-899 ◽  
Author(s):  
Rami Payman ◽  
Michael J. Lyon
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Volume Fraction ◽  
Regional Blood Flow ◽  
Injection Technique ◽  
Capillary Diameter ◽  
Capillary Surface ◽  
Capillary Length ◽  
Posterior Canal ◽  
Utricular Macula

Vascular compromise has long been proposed as a cause of inner ear disorders. However, the examination of blood flow and its control mechanisms in the vestibular system has been very limited. Combining stereological techniques with the microsphere injection technique, capillary morphology and regional blood flow were determined for the rat utricular macula. Results are as follows: total utricular blood flow 0.158 ± 0.078 μL/min; blood flow to the neuroepithelium (excluding nerve) 0.0995 ± 0.046 μL/min; blood flow per unit volume 7.71 ± 4.31 μL/min per cubic millimeter; neuroepithelial volume 0.01344 ± 0.0018 mm3; absolute capillary surface area 0.159 ± 0.039 mm2; mean capillary diameter 5.84 ± 0.56 μm; absolute capillary length 8.45 ± 1.6 mm; and capillary lumen volume fraction 0.0175 ± 0.004. Comparisons to previous data for the posterior canal ampulla indicate that the capillary diameter in the rat utricular macula is smaller; the capillary length is greater; and the end organs are similar with respect to neuroepithelial volume, capillary surface area, and blood flow. The size of the microsphere used in the present study (9.21 μm), in comparison to the mean capillary diameter (5.84 μm) of the utricular neuroepithelium, would indicate that the blood flow data likely represent a minimum value. These findings indirectly indicate that the utricular macula metabolic rate is greater than that of the posterior canal crista, and that there is variation from end organ to end organ in mean capillary diameter.

scholarly journals NEPHRON NUMBER IN THE OFFSPRING OF RATS FED A LOW PROTEIN DIET DURING PREGNANCY

2011 ◽  
Vol 19 (3) ◽  
pp. 219 ◽  
Author(s):  
Monika A Zimanyi ◽  
John F Bertram ◽  
Jane M Black
Keyword(s):  
Intrauterine Growth Retardation ◽  
Experimental Studies ◽  
Protein Diet ◽  
Low Protein Diet ◽  
Nephron Number ◽  
Intrauterine Growth ◽  
Nephron Endowment ◽  
Low Protein ◽  
Normal Protein Diet ◽  
Physical Disector

In experimental studies it has been shown that intrauterine growth retardation and reduced kidney growth during development are associated with significant decreases in nephron endowment. However, the results of previous studies may be inaccurate as nephron counts were obtained using a maceration technique, which can lead to breakdown of glomeruli, and other potentially biased techniques. In the present study, the total number of glomeruli (and thereby nephrons) in the offspring of rats fed a low (9%) or normal (20%) protein diet during pregnancy were estimated using a physical disector/fractionator technique. The offspring of rats fed a low protein diet had a significantly lower birth weight than rats fed a normal protein diet, their kidneys were smaller and they contained 30% fewer nephrons (20,386 ± 4,818 in the low protein diet vs. 28,731 ± 3,290 in the control rats). Our results, obtained using an unbiased stereological technique confirm previous findings that administration of a low protein diet during pregnancy results in reduced nephron endowment in the offspring.

A design-based method for estimating glomerular number in the developing kidney

2011 ◽  
Vol 300 (6) ◽  
pp. F1448-F1453 ◽  
Author(s):  
Luise A. Cullen-McEwen ◽  
James A. Armitage ◽  
Jens R. Nyengaard ◽  
Karen M. Moritz ◽  
John F. Bertram
Keyword(s):  
Lectin Histochemistry ◽  
Nephron Number ◽  
Nephron Endowment ◽  
Environmental Perturbations ◽  
Glomerular Number ◽  
Increased Risk ◽  
Developing Kidney ◽  
Unbiased Estimates ◽  
Rats And Mice ◽  
Physical Disector

Low glomerular (nephron) endowment has been associated with an increased risk of cardiovascular and renal disease in adulthood. Nephron endowment in humans is determined by 36 wk of gestation, while in rats and mice nephrogenesis ends several days after birth. Specific genes and environmental perturbations have been shown to regulate nephron endowment. Until now, design-based method for estimating nephron number in developing kidneys was unavailable. This was due in part to the difficulty associated with unambiguously identifying developing glomeruli in histological sections. Here, we describe a method that uses lectin histochemistry to identify developing glomeruli and the physical disector/fractionator principle to provide unbiased estimates of total glomerular number ( Nglom). We have characterized Nglom throughout development in kidneys from 76 rats and model this development with a 5-parameter logistic equation to predict Nglom from embryonic day 17.25 to adulthood ( r2 = 0.98). This approach represents the first design-based method with which to estimate Nglom in the developing kidney.

scholarly journals Nephron Endowment and Filtration Surface Area in the Kidney after Growth Restriction of Fetal Sheep

2004 ◽  
Vol 55 (5) ◽  
pp. 769-773 ◽  
Author(s):  
Eleanor K L Mitchell ◽  
Samantha Louey ◽  
Megan L Cock ◽  
Richard Harding ◽  
M Jane Black
Keyword(s):  
Surface Area ◽  
Growth Restriction ◽  
Fetal Sheep ◽  
Nephron Endowment ◽  
Filtration Surface

scholarly journals Is there an association between level of adult blood pressure and nephron number or renal filtration surface area?

2004 ◽  
Vol 65 (2) ◽  
pp. 582-588 ◽  
Author(s):  
M. Jane Black ◽  
Todd A. Briscoe ◽  
Marios Constantinou ◽  
Michelle M. Kett ◽  
John F. Bertram
Keyword(s):  
Blood Pressure ◽  
Surface Area ◽  
Nephron Number ◽  
Filtration Surface

Renal morphology and glomerular capillarisation in young adult sheep born moderately preterm

2020 ◽  
pp. 1-7
Author(s):  
Megan R. Sutherland ◽  
Waleed Malik ◽  
Vivian B. Nguyen ◽  
Vivian Tran ◽  
Graeme R. Polglase ◽  
...  
Keyword(s):  
Preterm Birth ◽  
Surface Area ◽  
Early Adulthood ◽  
Capillary Length ◽  
Renal Corpuscle ◽  
Adult Sheep ◽  
Glomerular Capillary ◽  
Renal Morphology ◽  
Increased Risk ◽  
Moderately Preterm

Abstract Preterm birth (delivery <37 weeks of gestation) is associated with impaired glomerular capillary growth in neonates; if this persists, it may be a contributing factor in the increased risk of hypertension and chronic kidney disease in people born preterm. Therefore, in this study, we aimed to determine the long-term impact of preterm birth on renal morphology, in adult sheep. Singleton male sheep were delivered moderately preterm at 132 days (~0.9) of gestation (n = 6) or at term (147 days gestation; n = 6) and euthanised at 14.5 months of age (early adulthood). Stereological methods were used to determine mean renal corpuscle and glomerular volumes, and glomerular capillary length and surface area, in the outer, mid and inner regions of the renal cortex. Glomerulosclerosis and interstitial collagen levels were assessed histologically. By 14.5 months of age, there was no difference between the term and preterm sheep in body or kidney weight. Renal corpuscle volume was significantly larger in the preterm sheep than the term sheep, with the preterm sheep exhibiting enlarged Bowman’s spaces; however, there was no difference in glomerular volume between groups, with no impact of preterm birth on capillary length or surface area per glomerulus. There was also no difference in interstitial collagen levels or glomerulosclerosis index between groups. Findings suggest that moderate preterm birth does not adversely affect glomerular structure in early adulthood. The enlarged Bowman’s space in the renal corpuscles of the preterm sheep kidneys, however, is of concern and merits further research into its cause and functional consequences.

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