Fig. 3: Specific deletion of Col1 in Fap-lineage cells leads to impaired skeletal development and late embryonic lethality.

a Genetic strategy to delete Col1a1 specifically in Fap-lineage cells by crossing the Col1a1^loxP/loxP mice with Fap-Cre mice. b Wild-type (WT; with genotype of Fap-Cre-negative;Col1a1^loxP/loxP) and Col1a1^fapKO (Fap-Cre;Col1a1^loxP/loxP) embryos at E16.5. The Col1a1^fapKO embryo exhibits hydrops fetalis (white arrow) and hemorrhage (red arrow). c Genotype distribution in live offspring documented examined at E9.5 and E12.5 from the crosses between Fap-Cre;Col1a1^loxP/+ and Col1a1^loxP/loxP mice. d–f H&E staining (d) and Col1 immunohistochemistry staining (e) of the embryos of WT and Col1a1^fapKO at E16.5. Quantification of % positive area for Col1 staining was based on three mice per group (f). The unpaired, two-tailed t test was used to compare the mean of two independent groups. **P = 0.00116 (tibia/fibula), ***P = 0.00057 (femur), **P = 0.00149 (radius/ulna). Data are represented as mean ± SEM. Additional Picrosirius Red staining was shown in Supplementary Fig. 4. g Genotype distribution in live offspring documented at the time of weaning from the crosses between Fap-Cre;Col1a1^loxP/+ and Col1a1^loxP/loxP mice. Scale bars of whole-mount sections, 5 mm; Scale bars at 50× magnification, 500 μm; Scale bars at 200× magnification, 100 μm.