Intracortical distribution of number and volume of glomeruli during postnatal maturation in the dog

Abstract

A B S T R A C T Morphometric analysis was carried out on kidneys of neonatal dogs in which function of the entire kidney and of single nephrons had been evaluated. Measurements were begun after neogenesis of nephrons had been completed, i.e., at the end of the 3rd postnatal wk. They were continued to 74 days by which time glomerular function, expressed per unit of renal weight, had reached the mature level. For statistical analysis, the cortical histogram at each age was divided into eight zones of equal depth between the capsule and corticomedullary junction.The mean total number of glomeruli in this beagle strain was 589 X 10' per kidney. The fraction of the total number of glomeruli was lowest in the subcapsular layer (3.9%) and highest (24.5%) in the zone immediately beneath from where it decreased almost linearly to a value of 4.5% in the juxtamedullary region. This numerical distribution did not change with age, which suggests that growth of nonglomerular structures proceeded at the same rate in all cortical layers.Volume of the glomerular tuft rose slightly between the subcapsular and next layer and remained constant down to the juxtamedullary region where it increased sharply. The juxtamedullary glomerulus was about 45% larger in volume than the other glomeruli. This intracortical distribution of glomerular volume did not vary between 23 and 74 days, although the volume of an individual glomerulus at each level increased slightly with age.

Determinación de Parámetros Estereológicos en el Riñón de Conejo (Oryctolagus cuniculus)

“…. The total number of rabbit Oryctolagus cuniculus glomerules, is less than that obtained in sheep by Eleanor et al (2004) of 559.000 ± 198.000 and in dogs by Horster et al (1971) of 589.000 and higher than in rats by Bertram et al (1992) of 31.764 ± 3.667. The glomerular volume was less than in rats (6.6 x 10 -4 ), than in sheep 4.39x10 -4 and higher than in dogs 1.2x10 -4 .…”

“…El número total de glomérulos del conejo Oryctolagus cuniculus, es menor al obtenido en ovejas por Eleanor et al (2004) de 559.000 ±198.000 y en perros por Horster et al (1971) de 589.000; y mayor que en ratas por Bertram et al (1992) los que existen no son recientes (Moore & Lukianoff, 1929).…”

Renal Reabsorption of Bicarbonate in Puppies: Effect of Extracellular Volume Contraction on the Renal Threshold for Bicarbonate

“…It has been demonstrated in infants [8] and in puppies [10] that growth of the kidney is due mainly to increased tubular mass, particularly at the level of the proximal tubule. On the basis of these morphologic findings, as well as of functional data suggesting that proximal tubular function during immaturity is relatively lower than glomerular function, we have suggested that fractional reabsorption in the proximal tubule may be less in the immature than in the mature animal [7].…”

Functional and morphologic maturation of superficial and juxtamedullary nephrons in the rat.

“…Single nephron glomerular filtration rate (SNGFR) of the superficial nephrons was measured by several investigators in the growing animal. From data collected in the dog, Horster (Horster, Kemler & Valtin, 1971;Horster & Valtin, 1974) calculated that the percentage of measured kidney glomerular filtration rate (GFR) accounted for by the filtration rate of superficial nephrons changed significantly from about between the first and fourth month of post-natal development in the dog. This observation points to a functional maturation proceeding from the inner toward the outer cortex.…”