Figure 8.

Larynx-trachea-lung explants grown in culture for 96 hours along with beads soaked in either normal saline or FGF18 were fixed, sectioned, and analyzed by H&E stain and immunohistochemistry. Larynx-trachea-lung explant grown with normal saline soaked beads ( *) developed a normal C-shaped tracheal cartilage ring (A, B, C), whereas a similar explant grown next to a FGF18 soaked bead (*) formed a malformed and hypertrophic cartilage ring (D, E, F). Figures A and D are H& E stains, B and E demonstrates Col2A1 expression, and C and F demonstrate Sox9 expression. Tracheal cartilage grown next to a normal saline soaked bead demonstrates a punctuate pattern of expression of Sox9 and a diffuse extracellular pattern expression of Col2A1. Tracheal cartilage grown next to a FGF18 soaked bead demonstrates the similar punctuate expression of Sox9 and diffuse extracellular staining with Col2A1. The one significant difference is that Sox9 expression in the FGF18 exposed tracheal cartilage seems to be higher at the edge of the cartilage closest to the FGF18 soaked bead. Sox9 expression can also be noted in the endoderm of adjacent lung tissue where its role is unknown. In this example the normal saline soaked bead was lost during processing of tissue. The (*) denotes the position of the bead relative to the trachea during culture. (t -trachea, e -esophagus, lu -lung)(All pictures are taken at 20X)