Figure 2

CG-1A is an early endogenous marker for limb precartilage condensations in vitro. (a-d) A microscopic field in a 2-day leg micromass culture showing (a) indirect immunolocalization of CG-1A, (b) staining with FITC-conjugated peanut agglutinin (PNA); and (c) DAPI. The same field was photographed under (d) phase-contrast microscopy. (e-f) 9-hour fixed cultures incubated with (e) HRP-conjugated PNA fail to show staining but when immunostained for (f) CG-1A show patchy "proto-condensations" at 9 h of incubation (black arrowheads). (g-h) 18-hour fixed cultures incubated with (g) HRP-conjugated PNA or immunostained for (h) CG-1A show fully formed condensations of similar spatial patterns. Images (a-h) are at same level of magnification; scale bar in (a) represents 0.2 mm.