ABSTRACT
The analysis of lethal phenotypes in developing mice usually begins with the evaluation of readily identiable features related to the individual animal, its littermates, and the dam. The nature of the parameters to be assessed and the procedures used during the examination will vary depending on both the developmental age of the presumed lethal event and the chronological age of the animals. In our experience, an optimal macroscopic analysis should involve the acquisition of qualitative and selected quantitative data. Certain endpoints and investigational methods are common to all developmental stages, while others are best suited to animals of a particular age. Techniques for specimen collection and macroscopic analysis are exible and, thus, may be adapted to suit the needs of individual laboratories and specic research questions. That said, due care must be taken to plan the examination in advance so that samples and quantitative measurements are acquired in an appropriate order and using methods
Sample Collection Practices during the Prenatal Period ........................................................................ 134 Removal of the Maternal Reproductive Tract ................................................................................... 134 Isolation of Preimplantation Embryos (GD 0-GD 4.5) .................................................................... 136 Isolation of Newly Implanted Embryos (GD 5.0-GD 7.0) ............................................................... 138 Isolation of Evolving Embryos (GD 7.5-GD 15.0) and Fetuses (GD 15.5-GD 19) ........................ 140
Euthanasia .................................................................................................................................... 140 Removal Using Scissors .............................................................................................................. 140 Removal Using Forceps ................................................................................................................141 Fixation of Embryos and Fetuses ..................................................................................................143 Histological Processing of Embryos and Fetuses .........................................................................145
Sample Collection Practices during the Postnatal Period ...................................................................... 146 Data Collection during Mouse Developmental Studies ..........................................................................148
