Early developing pig embryos mediate their own environment in the maternal tract

Area of Science:

• Reproductive biology and immunology
• Maternal-fetal interface signaling

Background:

• Successful pregnancy relies on the maternal tract providing an optimal environment for embryonic development.
• The molecular dialogue between the embryo and mother is crucial but not fully understood.
• Infertility and pregnancy failure highlight the need to decipher this complex communication.

Purpose of the Study:

• To define the local maternal tract response to the embryo during early pregnancy.
• To identify molecular signals involved in the embryo-maternal dialogue.

Main Methods:

• Utilized a novel in vivo experimental model in sows to minimize genetic variability.
• Employed laparoscopic insemination and oviductal injection with spermatozoa or diluent.
• Analyzed gene expression using Affymetrix microarray in oviduct and uterine horn samples containing embryos or oocytes.

Main Results:

• Microarray analysis revealed down-regulation of most transcripts in the uterine horn in response to blastocysts compared to oocytes.
• Many altered transcripts in the uterine horn were related to the immune system.
• An in silico mathematical model demonstrated the embryo's role in modulating the maternal immune response.

Conclusions:

• The embryo acts as a modulator of the maternal immune system.
• Modest changes induced by the embryo can regulate the maternal immune response.
• This immune regulation likely allows the uterus to tolerate the embryo and support its development, crucial for successful pregnancy.