Tenascin-Y in the developing and adult avian nervous system

The glycoproteins tenascin-C and tenascin-R are abundant in the developing and adult nervous system, respectively. We have used a polyclonal antiserum to determine if tenascin-Y, a novel member of the tenascin family previously identified in the extracellular matrix of muscle, is also expressed in the avian nervous system. Beginning at embryonic day 3 tenascin-Y immunoreactivity is associated with bottle-shaped ependymal cells in the roof plate and floor plate of the spinal cord and brain. These cells resemble the secretory cells that synthesize the ventricular extracellular matrix, including Reissner's fiber. Tenascin-Y immunoreactivity is also seen in pia mater and blood vessels in the developing and adult central nervous system. Anti-tenascin-Y stains the connective tissue sheath of peripheral nerves and the dorsal roots beginning around embryonic day 20. In vitro, sensory neurites fail to form lamellipodia when cultured in the presence of recombinant tenascin-Y, suggesting that tenascin-Y may play a role in inhibiting sensory neurite regeneration into the spinal cord. There is little overlap in the expression patterns of tenascin-Y and tenascin-C during development and between tenascin-Y and tenascin-R in the adult central nervous system, which is further evidence of distinctive mechanisms of gene regulation by the different members of the tenascin family.