ABSTRACT
The foundation of phenotypic analysis in developing mice is qualitative assessment for structural defects and functional deciencies. Anatomic anomalies that can be detected in this fashion include alterations in the (1) location, (2) number, (3) shape, (4) size, and/or (5) architecture of organs, tissues, and cell populations. The rst morphological information suggesting that a developmental defect is present will show that a change in one of these ve parameters is present while providing an estimate of its extent. Such qualitative structural descriptions are often sufcient to address the research question of a given developmental pathology study. A common follow-on step in the evaluation is to combine a qualitative in situ assessment of gene expression (Chapter 10) or protein location (Chapter 11) with quantitative measurement of the same gene or protein in homogenized tissue. The technical difculties and laborious nature of gathering quantitative data for morphological endpoints sometimes preclude such testing in mouse developmental pathology studies. Nevertheless, some research questions may only be addressed using quantitative anatomic methods, such as whether an enlarged structure is bigger due to increased cell proliferation, decreased cell death, larger cell proles, or any combination of the three. Such studies have been simplied in recent years using computer-assisted techniques, although simple endpoints may be acquired manually.
