Definition: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Input: Abstract: The development of mouse and human embryos was assessed in human amniotic fluid to determine its suitability as a culture medium for human in vitro fertilization (IVF). Two-cell mouse embryos developed to blastocysts after 72 hours at rates similar to that in Whittingham's T6 + 10% fetal calf serum. Significantly more mouse embryos hatched in amniotic fluid. No difference was found between individual patient's amniotic fluids obtained at 16 to 21 weeks' gestation. A preliminary trial comparing amniotic fluid with T6 + maternal serum in human IVF showed no significant difference in fertilization rate and embryo development during 42 to 48 hours in vitro. Expanded blastocysts were obtained in amniotic fluid after 5 days in vitro. Four pregnancies were obtained in 9 patients' transferred embryos grown in amniotic fluid and with 2 or 12 patients' transferred embryos grown in T6 + maternal serum.

Human