Bernard Sass

Precursor Lesions and Pathogenesis of Spontaneous Mammary Tumors in Mice

A histologic study was done on the spontaneously occuring precursor and neoplastic lesions of mammary gland in inbred and hybrid female mice. Hyperplastic alveolar nodules (HAN) are small groups of non-encapsulated mammary acini lined by a single layer of low cubodial epithelial cells. The stroma of HAN often contain macrophages laden with ceroid pigment, which imparts to them a yellow color. Microfoci of carcinoma may be found within HAN, and adenoacanthomas may arise within acini in which there is chronic inflammation. Plaques are pregnancy-dependent lesions which occur in three albino mouse strains: DD, GRS, and RIII. These plaques are disc-shaped, are circumscribed or unencapsulated, have a central myxomatous core, and have acini which exhibit radial symmetry. Plaques can give rise to adenocarcinomas type P, type B (papillary and cystic) and also to the unusual and distinctive pale cell carcinoma. The spontaneous tumors described in this paper are mammary gland adenocarcinomas with sebaceous cell nests, tumors which are papillomas and contain basal epithelial elements and acini derived from mammary, sebaceous glands, or hair follicles.

Spontaneous Nephroblastoma in a Strain CE/J Mouse. A Case Report

Spontaneous kidney tumors, including nephroblastomas, are rare in mice (6, 8, 16, 27, 30) and rats (8, 14, 15, 17, 29). A single spontaneously occurring nephroblastoma, termed a Wilms tumor, ofa 23Ih-month-old RF mouse has been illustrated (8). A second spontaneously occurring nephroblastoma in a male SPFt Swiss(Webster-derived) mouse was tabulated but not described or illustrated (26). We have found no other documented reports of spontaneous nephroblastoma in mice. The purpose of this communication is to present a case report of a spontaneous nephroblastoma in a mouse. Not only is this tumor ofexceedingly rare occurrence but also there has been confusion with regard to the criteria for diagnosis of nephroblastoma and its differentiation from mixed mesenchymal tumor, particularly of rats (4,8-11,31). A strain CEil breeder female mouse was killed at 17 months of age because of sluggishness and abdominal distention. At necropsy, a 6x l3-mm friable, greenish mass protruded from the cranial pole ofthe left kidney and extended to surround the left adrenal gland. On incision of the kidney in the midsagittal plane, the renal pelvis was distended by a dark green mass which was continuous with the mass attached to the cranial pole of the kidney and

Primary Tumors and Adenomatosis Of The Lung In Untreated and In Irradiated Guineá Pigs

The morphology of alveologenic tumor, hemangiosarcoma, lymphangioma, intrabronchial papilloma and adenomatosis observed in the lung of guinea pigs is described. Electron micrographs revealed alveologenic tumor to consist of Type II pneumocytes and the lesion of adenomatosis to consist of distended alveoli lined with ciliated bronchial type epithelial cells. A relationship between the dose of gamma or X-ray irradiation received and the frequency of guinea pigs with lung tumors could not be established. In guinea pigs, which survived over 20 months, the frequency of alveologenic tumors in the inbred strains was 23/107 in irradiated and 11/79 in untreated guinea pigs; this difference was statistically not significant. The frequency of tumor bearing inbred males (11/60) was significantly lower than of tumor bearing noninbred males (23/65). In the irradiated guinea pigs alveologenic tumors occurred earlier and tumor nodules in the lung were more numerous than in the untreated guinea pigs. Primary hemangiosarcoma involved the lung of one untreated and one irradiated strain 2 guinea pig. A single lymphangioma was found in an untreated inbred guinea pig. Intrabronchial papillomas were observed twice in irradiated and once in untreated guinea pigs. Adenomatosis was present in the lung of 2 untreated inbred and 5 irradiated noninbred guinea pigs.

Metastatic Tumors, Lung, Mouse

The spread of cancers to distant organs and the subsequent development of new foci present major challenges in research on tumor progression. Reports of spontaneously occurring mouse mammary tumors metastasizing to the lung first appeared in the early years of this century. Experiments with induced hepatic tumors and several types of transplanted tumors were reported but the pathogenesis of metastasis was still not understood. Metastasis involves several steps: detachment of cancer cells, either singly or in clumps, from the primary tumor; invasion of and subsequent passage within the vascular system to distant sites in which adhesion to and invasion and penetration of the vessel wall occur; and infiltration and growth in the pulmonary tissues. These steps are at present being investigated and will result in a better understanding of the pathogenesis of metastasis.

Detection and Cellular Localization of Lead by Electron Probe Analysis in the Diagnosis of Suspected Lead Poisoning in Rhesus Monkeys

Lead poisoning of unknown source was diagnosed histologically in 2 rhesus monkeys (Macaca mulatto) by finding acid-fast intranuclear inclusion bodies in the epithelial cells of renal cortical tubules. The presence of lead in the inclusions was determined by scanning electron microscopy/energy dispersive x-ray analysis using sections from paraffin embedded tissues. This observation indicates the usefulness of this technique for the detection and cellular localization of lead in tissues, even from archival material.