Abstract
Abstract: :
Recent studies from our laboratory have shown that the human cornea has a 5% increase in endothelial cell density (ECD) in the paracentral region and a 10–30% increase in ECD in the far peripheral region (next to Schwalbe’s line) compared to the central region. (Holley #3176 ARVO, 2002). Preliminary studies have proposed that adult stem cells maybe located in this region of the corneal endothelium (Whikehart #1627 ARVO, 2002). Purpose: To compare the ECD in the central, paracentral and peripheral regions of the mouse, rat and rabbit cornea. Methods: Corneas were obtained from euthanized mice (C–57 and CD–1 at 4.5 to 8.5 weeks), rats (CD–IGS at 50 weeks) and New Zealand White rabbits (10 weeks, 8 months, and 2.5 years). The corneas were excised with a small 2 mm scleral rim.The 4–6 radial incisions were made to the cornea so that a flat mount could be made of the endothelium. The endothelial surface was stained with 0.2% Alizarin Red for 7–12 minutes. The stained endothelium was then rinsed with sterile BSS. The flat mount was photographed with light microscopy and 100 contiguous cells were traced and digitized using the corners method. ECD, coefficient of variation and % hexagonal cells were determined for the three corneal regions. Results: Mouse ECD (mean±SD) were 2918±308, 2982±511 and 2720±446, respectively for the central, paracentral and perpherial regions. Rat ECD (mean+SD) were 2601±280, 2506±61 and 2196±54, respectively for the central, paracentral and peripheral regions. Rabbit ECD for the 10 week corneas (mean) were 3920, 4117, and 4059, respectively for central, paracentral and peripheral regions. Rabbit ECD for the 8 month corneas (mean) were 3673, 3312, and 2918, respectively for central, paracentral and peripheral. Rabbit ECD for the 2.5 yr corneas were (mean±SD) 2619±170, 2593±248, and 2308±216, respectively for central, paracentral and peripheral regions. Conclusions: The mouse, rat and rabbit corneas have a higher ECD centrally compared to the peripheral corneal region which is unlike the previously reported increase in peripheral ECD for the human cornea.
Keywords: cornea: endothelium • comparative anatomy • anatomy