During this period, blastocysts increase in diameter from 1.2 to 1.6 mm; there is then rapid enlargement from 1.7 to > 2.0 mm in diameter 1-2 days before implantation. The strong correlation between blastocyst diameter and developmental state of the embryo, in combination with changes in uterine weight, makes it possible to accurately classify uterine samples and establish the onset and stage of renewed embryonic development in this species. buy cheap antibiotics
LIF transcripts were significantly more abundant in uteri containing embryos 1.2-1.6 mm in diameter than in those containing blastocysts in diapause. The concentration of LIF mRNA in the uterine sample containing embryos earliest in activation (1.05-1.2 mm) was 1.6 times greater than the mean uterine LIF concentration during embryonic diapause. The concurrent increase in LIF mRNA at the onset of renewed embryonic development is consistent with the pattern of uterine LIF expression in the mink, and upon termination of facultative delayed implantation in the mouse. The observation that blastocysts appear to enter diapause upon arrival in the uterus of LIF -/- mice further emphasizes the relationship between elevated LIF expression and implantation.