Canine testicular tumors.With special reference to their histogensis, comparative morphology, and endocrinology

ANINE TESTIC~JLAR TuhioKs are oE unusual C interest for three reasons.1.They are so common that they afford the pathologist an excellent opportunity to study neoplasms in all stages of development.2. They have seemingly exact counterparts in the human, in whom they are considerably rarer.3.One variety, the Sertoli-cell tumor, is capable of elaborating estrogens; by so doing, it furnishes the most convincing evidence yet adduced for estrogen production by an individual cell type in the male gonad.17, 21, 25 have reported single as well as large series of cases studied from both morphological and endocrinological viewpoints.Their observations, where complementary to our own, will be presented. Numerous investigators3, 8-13, RIAT EKIAL AND METHODSOur material consisted of 177 surgical and autopsy specimens of testicular tumors encountered in eighty-six dogs over a four and onehalf-year period at the Angell Memorial Animal Hospital.T h e great majority of the tumors were recognized by gross examination of the involved testis; from these one or more blocks were cut, fixed i n formalin, embedded in paraffin, and stained with hematoxylin and eosin.Connective-tissue stains were done in certain cases.In addition, frozen sections of formalin-