Figure 1: Micrographs of the (incipient) knee joint of a 13.5 day murine embryo (a and b) and a 15.5 day murine embryo (c and d) obtained during laser microdissection. The area outlined in red was considered to be the intermediate layer of the interzone; the area outlined in green was the outer layer of the interzone and blue indicated epiphyseal cartilage. The top left micrograph (a) was taken at 200x magnification, all others (b, c, d) were taken at 100x magnification (see scale bar in bottom left corner of each image).