Figure 3

RBM19 is expressed in a dynamic pattern during preimplantation development. (a-d) RBM19 immunostaining in the 8-cell stage embryos localizes to cytoplasmic granules. In contrast, B23 is localized around the NPB. (e-h) In the early blastocyst, RBM19 begins to co-localize with B23 within nuclear foci, but is also noted in the cytoplasm. (i-l) In the mid-blastocyst, the inner cell mass (ICM) is becoming more distinct (oriented toward 5 o'clock) and RBM19 continues to co-localize increasingly with B23. RBM19 is retained in the cytoplasm to a greater extent in the cells that are located in the presumptive ICM. (M-P) In the late blastocyst the ICM is easily identified oriented toward 2 o'clock. The localization of RBM19 is mostly concordant with B23 thereafter.