Tenascins are expressed in distinctive and dynamic patterns during development. Photo shows a section through the small intestine of a 17-day-old chicken embryo. Double-label indirect immunohistochemistry was used to localize tenascin-Y (the avian homologue of tenascin-X, identified with a red Alexa 594-tagged secondary antibody) and tenascin-R (identified with a green Alexa 488-taged secondary antibody). Tenascin-Y is concentrated in extracellular matrix of the muscularis mucosa, whereas the expression of tenascin-R is restricted to the autonomic nervous system. See Meloty-Kapella et al., Developmental Dynamics 235:1532–1542. © 2006 Wiley-Liss, Inc.