Cytoplasmic Inclusions in Estrogen-Induced Testicular Interstitial-Cell Tumors in Mice2

Abstract

Numerous large, cytoplasmic inclusions have been observed in a testicular interstitial-cell tumor line that arose after estrogen treatment in a hybrid mouse, A × BALB/c. The inclusions were clearly visible under light microscopy as acidophilic bodies. They stained intensely with toluidine blue and were periodic acid-Schiff and Feulgen negative. Electron micrographs revealed that the inclusions were composed of type-A viral particles of very uniform shape and size, 76 mµ outside diameter. This discovery led to a systematic search for similar inclusions in Leydig-cell tumors of hybrid and inbred BALB/c strains. Inclusion bodies were also found in other testicular tumor lines that originated in inbred BALB/c and in hybrid, A × BALB/c and (57 × BALB/c, mice. By their staining characteristics and properties at the light microscope level and by their fine structure under electron microscopy, the cytoplasmic inclusions of the 3 AA testicular tumor line resembled those already reported in other murine tumors.