ABSTRACT
The cycads are a group of relict Mesozoic plants of which 10 genera now exist in the mainly tropical to warm temperate regions of the world. An additional toxicity which affects cattle after weeks of consumption of cycad leaves is a posterior ataxia known locally as “zamia staggers”. A toxin responsible for this condition has not so far been discovered. Although in the original acute toxicity studies with the compound in chickens, mice and rats, a neurotoxic effect was observed, no neuropathological changes were reported. Lately the acute toxic effects of this compound in young rats was confirmed and specific anatomical changes in the brain recorded. Electron microscopic changes were also apparent at six hours and apart from degeneration of neuronal cytoplasmic components in affected stellate cells, there was swelling of Purkinje cell dendrites which contained masses of myelin figure-like material.
