Fig. 5

Osteoprogenitors express esrp1 and cdh11 in a temporal pattern during fin regeneration

(A–C) Dual RNA ISH on cryosections from 1, 2, and 3 dpa fin regenerates using RNAScope. (A) Expression of esrp1 and cdh11 in a 1 dpa fin cryosection. (A1 inset) cdh11 only stained some cells lining the bone (black arrow, positive staining; orange arrows, no staining). cdh11 staining was also observed in cells around the fin ray joints (red arrowhead). (A2 inset) Cells staining for cdh11 were observed along the amputation plane, lining the distal border of the mesenchymal compartment (stars). (B) Expression of esrp1 and cdh11 in a 2 dpa fin cryosection. (B1 inset) cdh11+ cells were prominent along the fin bone, including near the fin joint (red arrowhead). (B2 inset) Multiple cdh11+ cells were observed near the amputation stump (stars). (B3 inset) Arrowhead indicates a cell staining positive for both esrp1 and cdh11 in the forming blastema. (C) Expression of esrp1 and cdh11 in a 3 dpa fin cryosection. (C1 inset) Prominent cdh11 expression is observed at the amputation stump. (C2 inset) Multiple cells showed staining for both cdh11 and esrp1 (arrowheads). (C3, C4 insets) Multiple cells in the lateral mesenchymal compartment were positive for esrp1 but not cdh11 (yellow arrowheads).

(D–E) Dual RNA ISH for twist2 and cdh11 on cryosections from 1 and 3 dpa fin regenerates. twist2+/cdh11- cells were scattered throughout the mesenchyme at both timepoints.

(D) twist2 and cdh11 expression in a 1 dpa fin cryosection. twist2+/cdh11+ cells were detected along the native bone (D1 inset) and the amputation stump (D2 inset) (white arrowheads). (D3 inset) Some cdh11+ cells along the native bone did not express twist2 (black arrowheads).

(E) twist2 and cdh11 expression in a 3 dpa fin cryosection. (E1 inset) twist2+/cdh11+ cells were detected along the native bone (white arrowheads). (E2 inset) Expression of twist2 was less prominent in the proximal lateral mesenchymal compartment than cdh11, although small clusters of cdh11+ cells stained strongly for twist2 (white arrowhead). (E3 inset) Robust twist2 expression was observed in distal cdh11+ cells. All scale bars are 60 μm. Amputation plane is indicated with dashed yellow line.