Cytokines, decidua, and early pregnancy.

Cytokines and other small signalling molecules appear to play important roles in determining the success or failure of early pregnancy. Much more information is needed, particularly with respect to interaction effects of the multiple cytokines present in situ and matrix molecules. Further, this author would like to emphasize the importance of experiments which test in vivo the physiologic relevance of factors detected in samples of reproductive tissues using in vitro methods, existentialism notwithstanding.