Two cell kinetic methods studied on the rat corneal epithelium

A stathmokinetic method (using Colcemid) and the [3H]thymidine technique (pulse labelling with tritiated thymidine, [3H]TdR) have been evaluated in the rat corneal epithelium. The dose is not of critical importance for the Colcemid method, thus indicating an all or nothing effect within the dose range studied. A one point estimate is sufficient to calculate the mitotic rate (MR), and in the rat corneal epithelium a 4 h accumulation period is recommended. After administration of [3H]TdR there is an increasing response with increasing dose, followed by a levelling off at higher doses. It seems reasonable to use the lowest maximal effective dose. The labelling index (LI) can be reliably registered 1 h after administration of the drug. For each of the drugs we found corresponding results after topical application and intraperitoneal injection. Hence, topical application of small doses of both Colcemid and [3H]TdR makes interesting in vivo experiments on larger animals and even on human beings possible. Due to the extreme regularity of the corneal epithelium this part of the eye is an interesting organ for cell kinetic studies and provides an excellent tool for evaluating cell kinetic methods.