A reproducible method for injecting the mouse corneal stroma.

An improved delivery system for injecting the mouse corneal stroma was developed. This system incorporates the following features: a repeating dispenser that eliminates inaccuracies in depressing a syringe plunger, foot activation which frees both hands for manipulating the needle and permits constant observation of the injection site, and a flexible 30-cm, 32-gauge stainless steel needle with a 30 degrees bevel and a locking hub that resists pulsation due to back pressure while permitting freedom of motion by the operator. These injections were done while observing the cornea with a vertically mounted slit lamp, ideally suited for examining and photographing the eyes of laboratory animals. The reproducibility of the new delivery system, expressed in terms of the signal-to-noise ratio, was estimated and compared with that of a hand-held microsyringe by injecting a solution of radioactive chromium into the corneal stroma of A/J mice. The eyes were removed within 1 hr of injection, and the amount of chromium in each eye was determined in a gamma counter. The new delivery system had significantly (P less than 0.05) greater reproducibility than the hand-held syringe and could be calibrated to deliver up to 0.65 microliter to the mouse cornea.