Fig. 1.

Immunofluorescence staining of type XII collagen on chicken tendon at developmental stages days 14, 17 and 19. Developing chicken tendons from day 14 to 19 were reacted with antibodies against type XII collagen either long isoform or both isoforms. Reactivity with antibodies against type XII collagen both isoforms (A, C and E) was present at all stages observed, with strong and homogenous signal at day 14. A localization of type XII collagen reactivity was observed beginning at day 17, and was prominent at day 19 in the matrix region surrounding the growing fascicles (arrows). Reactivity with antibodies against long isoform was also detected throughout the stages with homogenous distribution at day 14 and enriched endotendinium staining from day 19 (B, D and F) (arrows). Images presented demonstrated the shift in spatial distribution from the tendon proper (arrowheads) at early stages (14D) to the sheath in mature tendon (19D). In all cases, the negative controls (absence of primary antibodies) were negative (data not shown). OS = outer sheath. Bar = 10 µm.