Laboratory Animals: Evaluation With the Rostock Cornea Module of the HRT II

Abstract

Purpose: : The aim of the present study was to describe the use of a new in vivo confocal microscope to evaluate the cornea of three commonly used laboratory animals.

Methods: : Six eyes of three adult male New Zealand albino rabbits, six eyes of three adult male Lewis rats and six eyes of three adult male Swiss mice were used in this study. Corneas were analyzed in vivo using the Rostock cornea module of the HRT II. For all eyes, twenty confocal microscopic images of each layer, i.e. the superficial and basal corneal epithelia, Bowman’s layer, the anterior and posterior stroma and the endothelium were recorded. The images were then analyzed qualitatively and compared between animals. Cellular density of anterior and posterior stroma keratocytes of rabbits and endothelium density of the three different animals were also measured and compared.

Results: : The Rostock Cornea Module of the HRT II was successfully used to analyze all corneal layers of these three commonly used laboratory animals. Although the cellular patterns of corneal layers of these three animals as observed with in vivo confocal microscopy were quite similar, some differences were seen in terms of endothelial cells density and stroma appearance. Superficial cells were seen as hyper– and hypo–reflective polygonal cells. Basal cells had dark cytoplasm without visible nuclei and were closely organized. A Bowman’s layer could be observed in all three animals as an amorphous tissue containing fine subepithelial nerve plexus. In rabbits, the stroma consisted of an amorphous ground substance with hyper–reflective structures corresponding to keratocyte nuclei. In rats and mice, the stroma was irregularly reflective but no nucleus or cell could be observed. Besides endothelial cell density, the endothelium was similar among the three animals and was seen as hyper–reflective cells with dark limits organized in a honeycomb pattern.

Conclusions: : The Rostock Cornea Module of the HRT II can provide in vivo high resolution images of all corneal layers of rabbits, rats and mice without sacrificing animals or performing tissue preparation. This new device may be extremely useful for evaluation of the cornea during animal experimental studies.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • pathology: experimental • anatomy