Original Paper

Assessment of the Apparent Intra- and Inter-Sample Variability in the Collagen Fibril Diameter in the Posterior Corneal Stroma of Rabbits
A Transmission Electron Microscopy Study
Michael J. Doughty, Jan P.G. Bergmanson

Texas Eye Research and Technology Center, University of Houston College of Optometry, University of Houston, Houston, Tex., USA

Address of Corresponding Author

Ophthalmic Res 2006;38:335-342 (DOI: 10.1159/000096228)

  Key Words

• Collagen fibrils
• Cornea
• Diameter
• Morphometry

  Abstract

Purpose: To assess the natural variability in the diameter of small collagen fibrils in the lamellae of corneal stroma of healthy young rabbits. Materials and Methods: The corneas of 6 young adult female New Zealand White rabbits (2.1 kg) were prepared for transmission electron microscopy (TEM) by fixation with a cacodylate-buffered 2% glutaraldehyde (pH 7.2-7.4, 320-340 mosm/kg). The corneas were embedded in Epon-Araldite, thin sections prepared from the central region of the posterior corneal stroma and stained with acidic uranyl acetate followed by acidic lead citrate. High magnification (×33,000) micrographs were taken, and fibril diameters (FDs) measured at a final magnification of ×275,000 to a resolution of 2 nm. Results: Assessment of sampling-related errors indicated that the average diameter of the fibrils within any particular micrograph could be estimated to within 1% or better by measures of 100 fibrils. Assessments of the intra-sample variance (6 micrographs taken from the same cornea) indicated a group mean FD of 32.4 ± 3.6 nm, whilst the inter-sample variance (6 micrographs taken from 6 different corneas) yielded an average of 33.1 ± 4.5 nm (n = 100 fibrils/micrograph, ±SD). However, group-averaged data sets of FDs, while unimodal, were not normally distributed, and cumulative averaging indicated a fixed range of FDs across the data sets. Conclusions: Intra- and inter-sample variability in collagen FDs is very similar, but the analysis indicates that the collagen fibrils are not homogeneous and that closely adjacent lamellae can have subtle differences in average FD.

Copyright © 2006 S. Karger AG, Basel

  Author Contacts

J.P.G. Bergmanson
Texas Eye Research and Technology Center
University of Houston College of Optometry, University of Houston
Houston, TX 77204-2020 (USA)
Tel. +1 713 743 1950, Fax +1 713 743 3057, E-Mail Jbergmanson@UH.edu

  Article Information

Received: November 8, 2005
Accepted after revision: July 27, 2006
Published online: October 13, 2006
Number of Print Pages : 8
Number of Figures : 4, Number of Tables : 1, Number of References : 22