In situ mRNA hybridization of genes encoding extracellular proteins implicated in cartilage and bone formation in the head region.

<p>Sagittal sections of the head region of 28 dpf zebrafish juveniles stained by acid-free bone (red) and cartilage (blue) staining (A-B), or used for in situ hybridization with an antisense RNA probe corresponding to lect1 (C), ucmab (D), bmper (E), col1a2 (F). As a control, hybridization with the lect1 sense RNA probe is shown (G). (B-G) Magnification of boxed area in A focusing on the parachordal (pch) cartilage. Images are from consecutive sections at the same position. (C-D) Expression of lect1 and ucmab is located in chondrocytes of the parachordal (pch) cartilage (arrows). (E-F) Transcripts of bmper and col1a2 were detected in ossification sites surrounding the parachondral chondrocytes (arrow heads). Scale bars indicate 0.5 mm (black), or 100 µm (white). Abbreviations: ep, ethmoid plate; Mk, Meckel’s cartilage; oc, otic capsule; pch, parachordal.