Pathology of Tumors of the External Ear in Mice Induced by Ultraviolet Radiation

Abstract

This paper deals with the gross and histologic features of tumors of the external ear induced in male mice of strain A by ultraviolet radiation according to the technique discussed in the preceding paper (1). Details of dosage, intensity, and incidence data may be found therein. Tumors of the external ear have been adopted as the basis for incidence studies since in a total of 147 tumor-bearing mice the external ear has been involved in 144. Tumors of the eye have developed in 6 mice, 3 in combination with tumors of the ear and 3 without tumor elsewhere. These latter have not been included in the incidence data, and the 3 animals bearing tumors of both eye and ear have been listed as positive for statistical purposes only when the tumor of the ear appeared. When a tumor appeared on the external ear the animal was killed by cervical dislocation, and both ears and cervical lymph nodes were immediately placed in Zenker's fluid containing 5 percent of acetic acid. Histologic examination of the Bars and cervical nodes was made in every instance, and any other lesions observed at autopsy were allo examined histologically. Tissues were embedded in paraffin. The haematoxylin-eosin stain was employed routinely; other stains employed on occasion were Mallory's phosphotungstic-acid haematoxylin, Mallory's aniline blue, and Wilder's or Foot's methodsfordemonstrating reticulum.