Space Balls Revisited: Stereological Estimates of Length With Virtual Isotropic Surface Probes

Abstract

The space ball probe was fully described in the literature 15 years ago by Mouton et al. (2002). Since then, it has been used in a number of studies in the nervous system that focus on axon, dendrite, and capillary length. The length of structural parameters in tissues reflect functional aspects of the tissues. Here, some of the various applications of this methodology will be presented, along with a review of the salient features of the methodology that has resulted in new wave of quantitative morphological studies of length in the nervous system. The validity of the method is discussed in view of its widespread use along with insights into the problems associated with its application to histological tissue and future techniques for applying space balls.

Serotonergic innervation of the human amygdala and evolutionary implications

“…Another limitation of this study, particularly regarding the direct comparisons of SERT‐ir axon density values in the humans and apes, is the possibility of differential shrinkage of human and ape tissue during processing and immunohistochemical staining. This variable cannot be corrected in quantitative measures of length, including measures used to calculate SERT‐ir axon density (MBF Bioscience Stereo Investigator User Guide V9; West, ). Additionally, the present human study and the Stimpson et al () study were conducted by different research groups, so inter‐rater reliability was not established between our human data set and the published ape data sets.…”

Changes in Thalamic Dopamine Innervation in a Progressive Parkinson's Disease Model in Monkeys

“…20 This stereological approach has been previously used to generate unbiased, reliable, and more efficient results than other quantitative analysis methods. 20,23 The use of parasagittal sections has optimized the stereological study, particularly for estimating DAT-ir axon length in R, where the anterior portion is the most densely innervated by dopamine. The use of the hemispherical probe for length estimation has the advantage of being isotropic by itself, not requiring orientation in different planes for its proper use, as with virtual planes.…”

“…The total length of DAT‐ir axons was estimated by a blinded investigator (M.H.G.M.) using the spaceball stereological approach . We used hemispherical probes combined with unbiased fractionator sampling implemented by StereoInvestigator software (v9.10; MicroBrightField Bioscience, Williston, VT); see Supporting Figure S1D,E.…”

“…Motor signs were assessed through the validated Kurlan motor score (range, 0-29 points). 16 Macaques that exhibited evident parkinsonian signs after the last MPTP injection and that remained affected thereafter until sacrifice were classified as parkinsonian (n = 8; motor score, [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Macaques that maintained normal motor features after the last MPTP dose were considered nonsymptomatic (n = 8); see Supporting Table S1.…”

“…using the spaceball stereological approach. 19,20 We used hemispherical probes combined with unbiased fractionator sampling implemented by StereoInvestigator software (v9.10; MicroBrightField Bioscience, Williston, VT); see Supporting Figure S1D,E. This software controlled the motorized stage of the Zeiss microscope and provided interactive test grids and probes.…”