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. 2013 Sep 9;8(9):e75012. doi: 10.1371/journal.pone.0075012

Figure 2. Immunofluorescence staining of different collagen types in a human developing embryonic proximal tibia (gestational day 54).

Figure 2

(A) Localization of the embryonic isoform of type II procollagen (type IIA) in the extracellular matrix (ECM). The anti-IIA antibody recognizes the exon 2-encoded cysteine-rich domain present in the amino propeptide of type IIA procollagen [43]. These IIA isoforms are generated predominantly by progenitor chondrocytes seen at the periphery and most proximal area of the developing tibia. Some expression of IIA procollagen has been reported in the pre-hypertrophic and hypertrophic region of developing cartilage [58] and is also shown here. (B) Type I collagen staining is restricted to the areas of precursor chondrocytes and cells of the perichondrium/periosteum. (C) Type II collagen staining patterns (i.e. the processed triple helical domain of type II collagen) is present throughout the entire developing limb. (D) Collagen X staining is restricted to the ECM containing hypertrophic chondrocytes. Cell nuclei are visualized in blue by DAPI staining. Scale bars = 100 µm. Immunofluorescent images are representative of three independent experiments using gestational day 54 tissue sections from different embryos.