Interleukin-6 and leukemia inhibitory factor differentially modify embryonic disk composition in post hatching bovine...

Area of Science:

• * Reproductive Biology
• * Embryology
• * Animal Science

Background:

• * Proper embryonic disk formation is critical for successful pregnancy.
• * Understanding factors influencing early embryonic development in vitro is essential for improving assisted reproductive technologies.
• * Interleukin-6 (IL6) and Leukemia Inhibitory Factor (LIF) are cytokines with known roles in mammalian development.

Purpose of the Study:

• * To investigate the effects of IL6 and LIF supplementation on bovine epiblast (EPI) and hypoblast (HYPO) development during extended in vitro culture.
• * To determine the optimal timing for IL6 and LIF exposure to influence post-hatching embryonic development.

Main Methods:

• * In vitro-produced (IVP) bovine embryos were cultured and supplemented with IL6 or LIF during specific developmental windows (days 5-12, 5-7, or 7-12 post-fertilization).
• * Embryo survival and hatching rates were monitored.
• * Immunofluorescent staining was used to assess EPI and HYPO cell numbers. Non-treated IVP embryos transferred in utero served as a reference.

Main Results:

• * Neither IL6 nor LIF supplementation affected embryo survival or hatching rates.
• * IL6 supplementation from days 5-12 or 7-12 post-fertilization significantly increased EPI cell numbers and decreased HYPO formation.
• * IL6 supplementation from days 5-7 had no effect, indicating a requirement for IL6 post-blastocyst formation.

Conclusions:

• * IL6 supplementation after blastocyst formation enhances bovine EPI development to levels comparable to in utero embryos.
• * This enhancement of EPI development by IL6 may come at the cost of reduced HYPO formation.
• * LIF did not replicate the effects of IL6 and had no significant impact on EPI or HYPO development.