Slide 2 contains four lesions that are
typical of spontaneous tumors induced by MMTV. However, two of the lesions
(Samples 1 and 2) were induced by transgenes rather than the virus. Slide
Sample 2-1 has a typical solid pattern of growth that has some glandular
differentiation and is refered to as a Type B tumor in the Dunn Classification.
However, this tumor was induced by the wnt10b transgene (Leder and Lane).
Sample 2 has the peculiar hyperplastic pattern seen in GR/A and RIII mice
known as the hormone dependent tumor or "plaque". However, this
particular hyperplasia is induced by the KGF transgene (Leder and Kitsberg).
Sample 3 has the microacinar pattern of a MMTV-induced mammary tumor. Sample
4 has a mixture of Type B and glandular and was induced by MMTV.