Aspects of the immunological relationship between mother and conceptus still remain a
mystery, although the recent advances in molecular biology have enlightened some of the
parameters that participate in fetomaternal cross-talk during implantation. The atypical
expression of major histocompatibility complex (MHC), the specific role of some hormones
and cytokines, as well as the temporal and spatial distributions of uterine natural killer cells,
represent substantive parameters of fetomaternal immunotolerance during implantation …