A SPONTANEOUS TESTICULAR TERATOMA IN AN ICR MOUSE

A spontaneous teratoma was detected in the left testis of a 7-wk-old m ale ICR (Crj:CD-1) mouse. The tumor was composed of a variety of well- differentiated tissue elements from all 3 germ layers including neuron al tissue and stratified epithelium as ectoderm-derived tissues, bone, cartilage, striated muscle, and adipose tissue as mesodermal tissues, and respiratory columnar epithelium as endoderm-originated tissue. No tumor metastasis was detected. It may be of congenital origin as in s train 129 mice. To the best of our knowledge, this is the first report concerning spontaneous testicular teratoma in a strain ICR mouse.