Pattern of tau isoforms expression during development in vivo.

Neuronal morphology and axonal growth during development are correlated to specific expression of various microtubule-associated protein tau isoforms. Using RT-PCR and Western blotting we found the unexpected result that the shift from fetal towards adult isoforms does not differ between rat cerebral cortex and cerebellum, two temporally differently developing areas. By immunohistochemistry we observed a cell type specific isoform expression during development and adulthood. The developmental expression of tau isoforms was compared to the appearance of stable microtubules assessed by the immunohistochemical detection of tubulin modifications. The tau isoform shift shows an apparent disconnect to neurogenesis, migration and volume growth, but coincides with the formation of synapses and the appearance of stable microtubules.