Figure 2.

Localization of dynamic and stable microtubules. (A-I) Dynamic, tyrosinated (Tyr; left panels), and stable, acetylated (Ac; middle panels), microtubules and their overlap in merged images (Tyr, green; Ac, red; right panels) in cultured hippocampal neurons are shown at 2 (A-C), 4 (D-F), 7 (G-I) and 19 DIV (J-L). High levels of Tyr-tubulin immunofluorescence were apparent throughout the dendritic arbor in all stages examined. In addition, Tyr-tubulin was concentrated at growing tips of dendrites early in development (2 to 7 DIV, arrowheads) and distal axons at all stages stages where the ends could be observed in relative isolation (arrows). Tyr-tubulin immunofluorescence was decreased within the axonal shafts compared to Ac-tubulin, apparent as red regions in merged images. In contrast, dendrites appear yellow-green, suggesting higher proportions of Tyr-tubulin to Ac-tubulin throughout the dendritic arbor. Scale bars: 20 μm.