Figure 2
Photoimages showing MMTV-infected mouse mammary tumors and several other patterns associated with tumors of non-GEM mice. (a) The acinar pattern typical of MMTV-infected FVB mice. It is composed of small clusters of cells organized around a small lumen. The nuclei are relatively small, oval and regular. This tumor was previously classified as type A and as an acinar carcinoma, low grade, MMTV-induced in the new classification. (scale bar=100 microns). (b) The solid, cord-like pattern of MMTV-infected mouse tumor. It is composed of solid cords of cells with little gland formation. The nuclei are relatively small, oval and but generally more pleomorphic that the acinar pattern tumor. It was previously classified as a type B tumor and as a solid carcinoma, low grade, MMTV-induced in the new classification. (Use scale bar in a) (c) The mixture of neoplastic glands and stratified squamous epithelium producing keratin. This tumor occasionally occurs in non-infected mouse strains such as FVB and more frequently in carcinogen-treated mice. This tumor is classified as an adenosquamous carcinoma. This specific tumor appeared in a transgenic MMTV-LTR/KGF mouse and illustrates the similarities of some GEM tumors with non-GEM tumors. (Use scale bar in a). (d) The combination of proliferating ducts and connective tissue was previous described as a Type P lesion. This lesion is found in mice that express the endogenous MMTV-2 and is associated with insertional activation of int-2. This lesion also appears in both the MMTV-LTR/int-2 and MMTV-LTR/KGF mice. This example is from a MMTV-LTR/KGF mouse and would be classified as a solid MIN. (Use scale bar in (a)). (e) A chemically induced pure squamous cell carcinoma of the mammary gland with no glandular differentiation formerly referred to as molluscoid tumor. Note that the squamous epithelium is producing acellular lamellar keratin. (Taken with 20×objective) (Photograph courtesy of Sabine Rehm). (f) A chemically induced adenomyoepithelioloma composed of proliferating myoepithelium and glands formerly referred to as type C tumor. (Taken with 40×objective) (Photograph courtesy of Sabine Rehm)
