My mentor, Sefton R. Wellings has pointed out the similarities between mouse and human mammary development and pathological lesions. His pioneering studies have only recently been accepted by the surgical pathology community. We worked as a surgical pathologist with Dr. Wellings for 30 years as well as being a "transgenic pathologist". We will point out the similarities that we have observed between the lesions found in the mouse and the human. Since there are an increasing array of lesions that are identical, we are confident that the mouse represents a very important model for human breast disease.
The bulk of lesions and tumors found in the wild type mouse do not resemble the common human lesions. The murine breast is significantly different in scale and structure. The experienced pathologist will have no difficulty distinguishing between the two. The mouse mammary fat pad is small relative to the size of the human breast. The human mammary ducts are sheathed in a dense connective tissue. The normal human has well developed terminal ducts and lobulo-alveolar units lying in a loose connective tissue. These and other factors influence our interpretation of the histopathology of the normal and abnormal mammary gland in the respective species.
"Spontaneous" mouse mammary tumor did not morphologically or biologically resemble most human breast cancers. However, the emergence of transgenic biology has provided remarkable evidence that mouse tumors produced by the same genes as human breast cancer result in tumors which resemble the human cancer.
We present a series of images from our archives. These image illustrate the remarkable similarity between the lesions in humans and those in mice transgenic mice. For example, the "sclerosing adenosis" found in humans has a counterpart found in transgenic mice with the activated src. Nodular tumors associated with the neu oncogenes in transgenic mice are morphologically indistinguishable from comedocarcinomas from the human mammary gland. Papillary carcinomas of humans resemble those of the PyV-MT mouse. Tubular tumors of human and mouse are similar. The common scirrhous carcinoma of the human breast has an identical counterpart in the mouse with an activated src transgene.
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