Ultrastructure of Tri-Ortho-Cresyl Phosphate poisoning in the chicken

Summary Electron-microscopic investigations of the spinal cord in adult chickens poisoned with TOCP (Tri-Ortho-Cresyl Phosphate) show pathological alterations as early as the first day after appearance of the clinical symptoms. Of the same qualitative order as in the peripheral nervous system, they refer to the nerve fibres in the white matter in form of primarily diseased axons, with proliferation of the endoplasmic reticulum and disintegration of the neurofilaments. In the grey substance of the anterior horn, in particular, one sees severe structural alterations in the boutons terminaux while the motoneurons are hardly modified. The most striking finding already in the early stage is a massive swelling of the spherical synaptic vesicles in the boutons of theS-type, attributed to axo-somatic synapses.This work was supported by the Swiss National Foundation (Grant No. 3503). Part of the work was carried out at the Research Laboratory, McLean Hospital, Belmont/Mass. under the direction of J. D. Robertson.