The recovery of organelle transport and microtubule integrity in myelinated axons that are frozen and thawed.

Myelinated axons of Xenopus laevis were rapidly frozen in liquid nitrogen and thawed in a potassium glutamate based medium. Organelles within isolated, thawed axons were visualized by light microscopy. After thawing, organelles were stationary for about 5 min. Following this quiescent period, organelles exhibited a low frequency oscillation in the longitudinal direction of the axon; some of the organelles then began to move in either the anterograde or retrograde directions. Electron microscopic examination of axonal cross sections showed that few microtubules were present immediately after thawing, but the numbers of microtubules recovered to approximately normal levels with a time course resembling that of the recovery of organelle transport. The effects of colchicine and taxol on the recovery of organelle transport and the microtubule content of axons was consistent with the hypothesis that the recovery in microtubule numbers was related to the recovery of organelle transport. Vanadate ions inhibited the recovery of organelle transport at concentrations known to inhibit dynein ATPase.