Spatial dynamics of mTOR pathway activity during bovine embryo development

The mTOR pathway regulates cell proliferation, growth, survival, and metabolism by integrating nutritional and growth factor signaling. In embryos, its activity is influenced by the availability of nutrients in the culture medium, and it can affect the first cellular differentiation event, driving trophectoderm (TE) formation in mice. We hypothesized that mTOR activity is increased in cells poised to become TE and in differentiated TE cells of early bovine embryos. To test this, we assessed mTOR pathway activity through immunofluorescence detection of phospho-S6 (pS6) using confocal microscopy. In morulae, pS6 activity was primarily observed in the outer cells and in early blastocysts, in the TE, while it disappeared in late blastocysts, suggesting a specific pattern for mTOR localization and activity during early embryonic development in bovine.