Histomorphology and ultrastructure of spontaneous pulmonary neoplasms in strain A mice.
The microscopic and ultrastructural characteristics of spontaneous pulmonary neoplasms in strain A (strA) mice are described. Fifty-one spontaneous lung tumors were identified in 34 out of 57, 11-23-month-old male strA/Hen mice. Grossly, all tumors appeared as yellow-white, discrete nodules ranging in size from 1.0-10 mm. Tumor types were randomly distributed throughout the lung; however, the right lung lobes were most frequently involved. Histologically, tumors were classified as adenoma (34/51) or carcinoma (17/51) as defined by standard histopathologic criteria. Adenomas were usually less than 4 mm in diameter and had solid (16/34), papillary (10/34), or mixed (8/34) histologic growth patterns. Carcinomas were usually greater than 4 mm in diameter and had papillary (13/17) or mixed (4/17) histologic growth patterns. Ultrastructurally, benign tumors consisted of solid or papillary areas of neoplastic type II-like cells. Cells comprising malignant tumors had varying ultrastructural characteristics ranging from well-differentiated alveolar cell types to undifferentiated cells having intracytoplasmic osmiophilic dense bodies, vacuoles, or few specialized organelles commonly observed in mature nonneoplastic pulmonary epithelial cells.
Dixon
D
D
National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Horton
J
J
Haseman
J K
JK
Talley
F
F
Greenwell
A
A
Nettesheim
P
P
Hook
G E
GE
Maronpot
R R
RR
D000236:Adenoma / Q000473:pathology; D000818:Animals; D002291:Carcinoma, Papillary / Q000473:pathology; D003537:Cystadenoma / Q000473:pathology; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology / Q000648:ultrastructure / Q000662:veterinary*; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D009373:Neoplasms, Germ Cell and Embryonal / Q000473:pathology; D012376:Rodent Diseases / Q000235:genetics / Q000473:pathology