Figure 3

Live embryo imaging of preimplantation and early postimplantation mouse embryos hemizygous for a constitutively expressed H2B-EGFP fluorescent fusion. (a) Single confocal optical section fluorescence overlay on a bright-field image of a 5-cell stage pre-implantation embryo. Two of the blastomeres are dividing synchronously and are in metaphase (pink arrowheads in b). (b) Dark-field projection of the entire rendered z-stack of x-y sections (n = 19), through the entire embryo shown in panel a. (c) Color-coded depth projection of the entire z-stack of x-y images for the embryo shown in the previous panels. (d) Single confocal optical section fluorescence overlay on a bright-field image of a blastocyst stage embryo. Inner cell mass (ICM) is to the top left corner and second polar body is on the bottom left, juxtaposed to the edge of the ICM. (e) Dark-field projection of half the rendered z-stack of x-y sections (n = 40, sections 1–19 were used for generating the projection), spanning half the embryo shown in panel d. Condensed chromosomes of nuclei in prophase (pink arrowheads) can be seen in three cells of the mural trophectoderm. Cells of the polar trophectoderm (green arrowhead) and inner cell mass (blue arrowhead) can also be distinguished by position within the half-blastocyst reconstruction. (f) Color-coded depth projection of the entire z-stack of x-y images for the embryo shown in the previous two panels. (g-h) Saggital views and rendered z-stacks of x-y images of an E5.75 (pre-streak stage) embryo. (g) Single optical confocal section fluorescence overlay on a bright-field image positioned half the way through the embryo. The brackets on the left illustrate the position of the embryonic (Em) and extraembryonic (Ex) regions of the embryo. (h) The same optical section with only the fluorescence image. Cells of the epiblast (blue arrowhead) and visceral endoderm (green arrowhead) can clearly be distinguished on the basis of position and nuclear morphology. Cells in mitosis can readily be distinguished within the embryo (pink arrowhead). (i) Color-coded depth projection of the stack of serial sections (n = 60), part of the series of which is shown in the previous two panels. Color-coded z-scale (upper right) applies to all projections and denotes distances along the z-axis (0–120 μm).