Ultrastructure of axotomized alpha and gamma motorneurons in the cat thoracic spinal cord

I. P. Johnson*, T. A. Sears

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


Using horseradish peroxidase as a retrograde marker, the ultrastructural response of alpha and gamma motoneuronal cell bodies in the cat thoracic spinal cord has been compared 1–8 days following intercostal nerve transection and ligation. By light microscopy, reduction of Nissl body size, together with nuclear and nucleolar alterations were seen in alpha motoneurons 4–8 days following axotomy, but not at any stage in axotomized gamma motoneurons. In the electron microscope, disorganization of Nissl body ultrastructure was seen in both alpha and gamma motoneurons 2 days following axotomy. Only in alpha motoneurons, however, did these disorganized Nissl bodies subsequently fragment into smaller pieces. Both alpha and gamma motoneurons lost synapses following axotomy, but the proportional loss from gamma motoneurons was two–fold greater than that from alpha motoneurons. Loss of synaptic terminals with flattened synaptic vesicles was two–fold higher than that of synaptic terminals with round synaptic vesicles from axotomized gamma motoneurons, whereas axotomized alpha motoneurons lost both types of synaptic terminal equally.

Original languageEnglish
Pages (from-to)149-163
Number of pages15
JournalNeuropathology and Applied Neurobiology
Issue number2
Publication statusPublished - 1 Jan 1989
Externally publishedYes


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