Fig. 1

Lentiviral injection of E8.0 mouse embryos achieves stable targeting of intestinal epithelium in adult mice. a Schematic diagram of the egg cylinder at embryonic days 7.75–8.0. Figure adapted from Ermakova et al. [9]. b Targeting of the endoderm on embryonic day 8 (E8.0) was achieved by ultrasound-guided microinjections as indicated by 4-s time-lapse images (see Suppl. Movie). A needle comes from the left piercing the embryo (centre frame) attached to a uterine horn. Silicone support (right) was used to stabilize the uterine horn for injections. Left: At 0 s, the embryo has been pierced and the needle tip (red arrow) rests in the small yolk sac cavity in an E8.0 embryo. Right: At 3.5 s, 69 nl of concentrated lentivirus has been injected into the yolk sac cavity leading to a small expansion of the yolk sac cavity (blue arrow). Images were extracted from the supplemental movie and cropped to highlight injection and embryo. c Example of the composite image analysis of transduced crypt fields from a luciferase (GFP)-infected mouse. Mouse embryos were injected at E8.0, injected mice were analysed at postnatal day 90. Scale bars: 5 mm. d Example fluorescent stereoscope images of small intestine crypt fields after transducing mice at E8.0 with an H2B-RFP lentiviral construct, resulting in nuclear red fluorescence staining of the transduced crypts. Crypt fields were defined as > 10 transduced crypts in direct contact or being in close proximity (< 5 crypts distance). Top: low magnification Z-stack image highlighting transduced jejunal crypts with associated RFP-positive villi. Bottom: high-magnification image of H2B-RFP transduced ileal field, with multiple individual transduced crypts visible. Scale bars: 500 μm