It is established that the conceptus-endometrium dialogue involves cytokines, growth factors and hormones. Given the crucial functions of the suppressor of cytokine signaling (SOCS) family proteins in cytokine signalling, we analyzed the expression and the regulation of CIS and SOCSs 1-3 transcripts during early pregnancy in the ovine endometrium. An overall stimulation of the SOCS transcripts was described in the pregnant ewes with two specific patterns. Unilaterally pregnant ewes confirmed the conceptus-produced factors as regulators of the SOCSs 1-3 expression at day 16 of pregnancy. Intrauterine injection of recombinant ovine interferon (IFN ) in cyclic ewes stimulated the expression of the SOCS mRNA with various potencies, therefore suggesting that the SOCS could take part in the negative regulation of the IFN signalling pathway.

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A common problem in research laboratories that study the mammalian embryo is the limited supply of live material. For this reason, new methods are constantly being developed and existing methods for in vitro models using cells in culture are being adapted to represent embryogenesis. Three-dimensional fluorescence in situ hybridization (3D-FISH) is an important tool to study where genomic sequences are positioned within nuclei without interfering with this 3D organization. When used in the embryo, this technique provides vital information about the distribution of specific sequences in relation to embryonic nuclear substructures such as nucleolar precursor bodies and chromocenters. In this chapter, we will present a detailed description of FISH in order to perform 3D-FISH in the early preimplantation murine embryos.