Methods for estimating the volume of individual glomeruli.
Methods for estimating the volume of individual glomeruli.


BACKGROUND
The Cavalieri and maximal planar area (MPA) methods are commonly used to measure the volume of individual glomeruli. Previous studies have suggested that the MPA method, which is less laborious, yields values that are much greater than those obtained by the Cavalieri method. The current study re-examined the relationship of MPA and Cavalieri values for glomerular volume in humans and rats.


METHODS
Both methods were used to measure the volume of 1201 glomeruli from 58 humans and 281 glomeruli from 15 rats. Tissue was embedded in Epon. Further mathematical analysis was performed to assess the extent to which deviation of glomeruli from spherical shape affects the relationship of values obtained by the MPA and Cavalieri methods.


RESULTS
MPA values exceeded Cavalieri values by an average of only 14 +/- 22% in humans and 6 +/- 16% in rats. The relationship of MPA to Cavalieri values was similar in individual humans and rats, with widely varying values for average glomerular volume. Neither the development of sclerosis nor the loss of any connection to a tubule affected the relationship of the MPA and Cavalieri values for the volume of individual glomeruli. Mathematical analysis showed that MPA values would not exceed Cavalieri values if glomeruli had ellipsoidal rather than spherical shape.


CONCLUSIONS
Similar values for glomerular volume are obtained using the Cavalieri and MPA methods in humans and rats.
Pagtalunan
M E
ME
Division of Nephrology, VA Palo Alto Health Care System and Stanford University, Palo Alto, Stanford, California 94304, USA.
Drachman
J A
JA
Meyer
T W
TW
D000818:Animals; D006801:Humans; D007678:Kidney Glomerulus / Q000473:pathology*; D008953:Models, Anatomic; D009398:Nephrology / Q000379:methods*; D009929:Organ Size; D051381:Rats