A CASE OF INTRACYTOPLASMIC EDEMA OF FOLLICULAR EPITHELIAL-CELLS IN RAT-THYROID

Hydropic change of follicular epithelial cells in the thyroid was obse rved in a female Fischer 344 rat. Microscopically follicular epithelia l cells were characterized by edematous swelling with weakly eosinophi lic and homogeneous cytoplasm. The cytoplasm was negative for periodic acid-Schiff reaction, and thyroxine- and thyroglobulin-immunohistoche mical reactions. Electron-microscopically, a small amount of amorphous substance was noted in remarkably dilated rough-surfaced endoplasmic reticulum (r-ER), and slight regressive changes of cytoplasmic organel la were also observed. These morphological changes may indicate that f ocal intracytoplasmic edema was occurred in r-ER, and that the change belonged to hydropic degeneration of the thyroid follicular cells in t he thyroid.