Select Histochemical and Immunohistochemical Methods to Investigate the Cell and Tissue Composition of the Mouse Placenta and Metrial Gland.

Mice as model organisms play a vital role in translational research for developmental biology by aiding our understanding of embryonic and placental evolution in health and various disease states. The close similarity between mouse and human placentas is a great asset in reproductive translational research, making the mouse one of the more prominent model organisms in this field. Mice are routinely used to investigate mechanisms of embryonic and placental development, often through experimental manipulations involving engineered or spontaneous genetic mutations and/or xenobiotic treatments. A crucial aspect of fully appreciating the mouse as a model organism for placental research is understanding the anatomy and physiology of the major embryonic (chorion, labyrinth, junctional zone, and yolk sac) and maternal (decidua basalis and metrial gland) placenta components, including knowledge of the specific cell types active during each gestational stage. This paper discusses histochemical and immunohistochemical (IHC) methods that highlight specific tissue layers and cell types present during normal development of the mouse placenta and maternal metrial gland. Altered numbers and/or locations of these common cell types have been demonstrated in embryonic lethal phenotypes, indicating that placental assessments must examine not only the tissue organization but also affected cell populations when determining the cause of early pregnancy loss.