Follicle Squash Preparations: Uses in Studies of Cell Kinetics Following Irradiation

Abstract

These investigations in CF 1 mice were undertaken to establish the usefulness of whole follicle squash preparations in kinetics studies of anagen matrix cell responses to ionizing radiation. The backs of mice were plucked and H 3 TdR (0.8 uCi/g) was injected intraperitoneally 15 minutes prior to irradiation. Animals were treated with 100 rads at 45 kv. Skin biopsies were fixed in cold acid alcohol for 24 hours, brought through graded alcohols to water, hydrolyzed in 1N HCl, and transferred to Schiff's reagent overnight. Individual follicles were dissected free and squashed on slides in 45% acetic acid. Auto-radiographs were made from squash preparations. Mitotic indices were reduced within 30 minutes after x-ray exposure (2.4% in control sites vs 1.8% in irradiated silos) and dropped sharply after 2 hours (2.2% vs 0.7%). There was essentially complete recovery of the mitotic index within 7 hours after irradiation (2.1% vs. 1.7%). The post-radiation G 2 period delay was 1½-2 hours. Studies of the 4 individual hair types revealed no significant differences in radiation responses despite substantial differences in the sizes of matrix cell populations. Usefulness of the technique described for kinetics studies of drug or radiation effects on proliferative cell populations is emphasized.