Tikrit Journal of Pure Science 23 (8) 2018 ISSN: 1813 – 1662 (Print) E-ISSN: 2415 – 1726 (On Line) 10 Tikrit Journal of Pure Science Journal Homepage: http://main.tu-jo.com/ojs/index.php/TJPS/index Electron Microscope Evaluation of late changes in the nerve fibers and neurons induced by Sciatic nerve section in rabbits Ban Ismael Sedeeq 1 , Ayad Hammeed Ibrahim 2 , Abul Kareem Salem Mahood 3 1 College of Dentistry, University of Tikrit, Tikrit, Iraq 2 College of Veterinary Medicine, University of Tikrit, Tikrit, Iraq 3 College of Medicine, Wasit University, Kut, Iraq A r t i c l e i n f o. Article history: -Received: 18 / 3 / 2018 -Accepted: 4 / 6 / 2018 -Available online: / / 2018 Keywords: sciatic nerve section, electron microscope, late changes, rabbit. Corresponding Author: Name: Ban Ismael Sedeeq E-mail: drbanasnan@gmail.com Tel: Abstract The aim of the study was to demonstrate late changes occurs after Sciatic nerve section [nerve fibers and their associated neurons]. Five adult rabbits were used in this study. Sciatic nerve was sectioned under general anesthesia. After ninety days, all animals were sacrificed and samples were taken from ventral horn of spinal cord, dorsal root ganglion at L₇ segment level and from sciatic nerve for electron microscope evaluation. The results revealed different changes include: separation of the myelin sheath lamellae within ventral horn, the Nissl bodies were scattered within sensory neuron thoughout the cytoplasm specially at the periphery, the cytoplasm contain numerous closed vesicles of different size associated with endoplasmic tubules and the myelin sheath usually forming a loop, axons seemed relatively smaller than normal. All of which are common features of axonal atrophy. Introductions Ultrastructural changes have been described in many organelles in the neurons during axon transection and most of the changes have been interpreted as acellular reorganization in preparation for axonal regeneration. However,yet there is little agreement about the various changes, and part the reports are mutually contradictory [1,2]. One reason for the conflicting findings could be related to species differences or different reactions in various nerve cell types [3]. Jirmanova clarified in his study on young chickens, the ultrastructural axotomized perikarya of spinal cord after peripheral nerves of the brachial plexus transaction. In axotomized neuron of spinal cord and during first post operative week, Nissl bodies are slightly reduced in size but remain scattered throughout the cytoplasm. Mitochondria and dense bodies generally increased in number are also dispersed in the cytoplasm. During second week, chromatolysis occurs in the majority of perikarya. The nuclei are displaced from their central position and in some instances almost touch the cytoplasmic membrane. The number of mitochondria and dense bodies massed in the central region increased during this week [4]. Zelena revealed different results in axotomized perikarya of sensory neurons after section in the nerves of brachial plexus. The majority of the axotomizedperikarya developed central chromatolysis In such neurons, Nissl bodies virtually disappeared from the central area of the neuron and formed more or less continuous zone at the cell circumference. The cytocentrum become filled with large numbers of mitochondria, dense bodies and other organelles. Neurofilaments and microtubules were disarranged and ran at random among the accumulated particles. Microtubules were often more prominent in chromatolytic areas than neurofilaments [5]. Most electron microscopic studies, clarified the acute changes occurs after nerve section, the present study was designated to demonstrate the late changes occurs after sciatic nerve section [at mid thigh region] in the nerve fibers and their associated neurons. Meterials and methods Five adult rabbits were used in this study. All were allowed free access to food and water before the experiment. The surgical operations were made under general anesthesia (IM) of [50 mg/kg] Ketamin hydrochloride with xylazine hydrochloride [10 mg/kg]. A longitudinal incision about 2.5 cm was made on the lateral side of the thigh parallel to longitudinal axis of Femur bone, and then separation between muscles continues until reaching the area where the sciatic nerve lies.