Purpose: We tested the hypothesis that cellular stress can induce developmental as well as homeostatic responses in embryonic (ES) and trophoblast (TS) stem cells. Methods: Murine ES and TS cells were cultured in the presence/absence of sorbitol. Growth rate was determined by counting cells using trypan blue exclusion and hemacytometer. Apoptosis was measured using Western blot analysis of cleaved-caspase 3 levels. Developmental responses were determined using Western blot analysis of pluripotency-regulating transcription factors and signaling proteins. Results: In TS cells, hyperosmotic stress activated AMPK and SAPK signaling pathways, leading to changes in the expression of key transcription factors which in turn allowed differentiation of these cells into giant cells. In ES cells, hyperosmotic stress led to the 50% loss of key regulators of pluripotency, Oct4, Sox2, and Nanog. Loss of these transcription factors was transient, however, and expression levels recovered to near baseline within 24h, preserving potency. Hyperosmolarity also induced an early loss of Rex1 transcription factor in ES cells, a loss maintained through 24hr, suggesting early lineage commitment. Conclusions: Hyperosmotic stress induced TS cells to take the next developmental step by differentiating, but did not have this effect on ES cells. These findings suggest strategies for optimizing the health of preimplantation embryos and stem cells, whether during in vitro fertilization procedures, the isolation and maintenance of high quality stem cells. or during the reprogramming of inducible pluripotent stem (PS) cells.