Analysis of mouse model pathology: a primer for studying the anatomic pathology of genetically engineered mice.

This primer of pathology is intended to introduce investigators to the structure (morphology) of cancer with an emphasis on genetically engineered mouse (GEM) models (GEMMs). We emphasize the necessity of using the entire biological context for the interpretation of anatomic pathology. Because the primary investigator is responsible for almost all of the information and procedures leading up to microscopic examination, they should also be responsible for documentation of experiments so that the microscopic interpretation can be rendered in context of the biology.

Manual immunohistochemistry staining of mouse tissues using the avidin-biotin complex (ABC) technique.

There are many variations on the immunohistochemistry (IHC) procedure, but all are based on attachment of a primary antibody to a unique epitope on or within the cell. This step is followed by incubation of the cell/primary antibody complex with another, secondary antibody that recognizes the species in which the primary antibody was produced. The secondary antibody has an indicator molecule attached to it.

Manual hematoxylin and eosin staining of mouse tissue sections.

The hematoxylin and eosin (H&E) stain is the standard used for microscopic examination of tissues that have been fixed, processed, embedded, and sectioned. It can be performed manually or by automation. For economic reasons, the manual technique is generally the method of choice for facilities with a low sample volume.

Mouse tissue fixation.

One of the primary goals of fixation is to stop postmortem changes that degrade the tissue and allow optimal preservation of morphologic and cytological detail as well as nucleic acid integrity. Following death, tissues soon undergo autolysis, and if organisms from the gastrointestinal, urinary, or respiratory tracts are present, their colonization can soon cause putrefaction. Time is of the essence because warmer temperatures accelerate both types of degradation.

Limited mouse necropsy.

Procurement of mouse tissues or organs is essential for complete verification of almost any phenotype. A proper necropsy can yield information that is difficult to obtain by limited biopsy or surgical intervention. The protocol described here is for a limited autopsy involving the thorax and abdomen only, and does not include all organs.

Structured reporting in anatomic pathology for coclinical trials: the caELMIR model.

Electronic media, with their tremendous potential for storing, retrieving, and integrating data, are an essential part of modern collaborative multidisciplinary science. Structured reporting is a fundamental aspect of keeping accurate, searchable electronic records. This discussion on structured reporting in anatomic pathology for pre- and coclinical trials in animal models provides background information for scientists who are not familiar with structured reporting.

Quantitation of fixative-induced morphologic and antigenic variation in mouse and human breast cancers.

Quantitative Image Analysis (QIA) of digitized whole slide images for morphometric parameters and immunohistochemistry of breast cancer antigens was used to evaluate the technical reproducibility, biological variability, and intratumoral heterogeneity in three transplantable mouse mammary tumor models of human breast cancer. The relative preservation of structure and immunogenicity of the three mouse models and three human breast cancers was also compared when fixed with representatives of four distinct classes of fixatives. The three mouse mammary tumor cell models were an ER+/PR+ model (SSM2), a Her2+ model (NDL), and a triple negative model (MET1).