Fig. 5: Trophoblast-like compartment integration and maturation in human SEMs.
From: Complete human day 14 post-implantation embryo models from naive ES cells
a, Top, representative immunofluorescence images of day 6 SEMs showing epiblast-like (OCT4), hypoblast/YS-like (SOX17 or GATA6), ExEM (GATA6) and trophoblast-like (SDC1, CK7 or GATA3) compartments. Bottom, single-channel images of the trophoblast-like compartment surrounding the SEMs. b, Average percentage of aggregates surrounded by a trophoblast-like compartment at day 6, as judged by the expression of SDC1, CK7 or GATA3. SDC1, N = 3 across 533, 232 and 94 aggregates; CK7, N = 5 across 302, 153, 344, 344 and 85 aggregates; and GATA3, N = 3 across 295, 170 and 62 aggregates. Error bars indicate the s.d. c, Left, z maximum intensity projection (z max) image of day 6 SEMs showing HCGB expression in the outer cells. Right, image of the same SEM showing lacunae-like structures (marked with asterisks) inside the outer syncytiotrophoblast-like layer. d, 3D projection of the lacunar-like structures (outlined) in the trophoblast-like layer of a day 6 SEM shown in c. Immunofluorescence for SDC1, HCGB and nuclei (DAPI). e, Histological section and 3D reconstruction (top right) reproduced from the Carnegie collection of a human embryo20 at CS5c showing lacunae in the syncytiotrophoblast (asterisks or box with dotted outline). f, Representative BF and immunofluorescence images of two different z planes (number 3 and 11, top and bottom, respectively) of day 6 SEMs showing epiblast-like (OCT4), hypoblast-like (SOX17) and trophoblast-like (SDC1) compartments. Top left, lacunae-like structures are outlined and marked with asterisks. Top right, zoom into the lacunae-like structure (top). Bottom, zoom into the outer syncytiotrophoblast-like layer. Brackets mark the thickness of syncytium-like tissue. g, Top, image of a day 6 SEM showing CK7, F-actin and nuclei (DAPI). Bottom, zoom into the multinucleated syncytiotrophoblast-like cell. Arrowheads indicate multiple nuclei inside the single cell. Scale bars, 10 µm (f, top zoom-in), 20 µm (d) or 50 µm (all other images).
