Fig. 1

LRP1 is abundantly expressed in skeletal progenitor cells, in particular in the perichondrium. a Representative images of immunohistochemical staining of LRP1 and fast green counterstaining in WT E13.5-P0 elbow joint sections of Lrp1^flox/flox mice. Scale bar, 200 µm. H, humerus; R, radius; U, ulna; PC, perichondrium. Regions delineated by the red squares in the panels have been magnified in the lower panels. Arrow heads indicate abundant LRP1 expression in perichondrium layers. b Schematic diagram showing the constructs used to generate skeletal progenitor-selective LRP1 conditional knockout mice. Transgenic mouse lines harbouring Prrx1 limb enhancer Cre (Tg 1) and floxed Lrp1 (Tg 2) were used to establish the Lrp1^flox/flox/Prrx1^Cre line. c In situ hybridisation chain reaction for Lrp1 and Fgf8 mRNA expression in E10.5 hind limbs of WT and Lrp1^flox/flox/Prrx1^Cre homozygote conditional KO (cKO) mice. Lrp1 and Fgf8 were visualised as described under “Materials and Methods”. L, bulging limb bud; S, somite. d Representative images of immunohistochemical staining of LRP1 and fast green counterstaining in E16.5 knee and rib sections of WT and Lrp1^flox/flox/Prrx1^Cre homozygote conditional KO (cKO) mice. Regions delineated by the red squares in the upper panels have been magnified in the lower panels. Scale bar, 200 µm. F, femur; T, tibia