The effects of an elevated temperature, colchicine, and vinblastine on axonal microtubules of the crayfish (Procambarus clarkii)

Microtubules of isolated crayfish ventral nerve cords rapidly dissociate at 40°C and upon reincubation at ambient temperatures part of the microtubule population transiently reforms. Colchicine had little effect on the structure or number of intact microtubules of unwarmed nerve connectives, but vinblastine caused a decrease in microtubular numbers and led to the formation of typical paracrystalline arrays. After warming, both colchicine and vinblastine treatment prevented microtubule reassembly, presumably by interacting with the heat‐induced microtubular dissociation products, and led to the formation of axoplasmic inclusions. The inclusions seen in vinblastine‐treated prewarmed connectives were identical to the paracrystalline arrays produced in unwarmed preparations but the inclusions seen following colchicine treatment of warmed connectives have a unique appearance and are ultrastructurally distinct from vinblastine‐induced arrays.