title: [Ultrastructural study on the facial nerve of rabbit after (125)I seed implantation].
abstract: OBJECTIVE
  To investigate the ultrastructural variation of the facial nerve of rabbit with different dosage of (125)I seed brachytherapy.
  
  
  METHODS
  Fifty-four big ear rabbits were divided into 3 groups randomly and given 40 Gy, 80 Gy, 120 Gy respectively. Radioactive seeds were implanted in one side of parotid gland, the other side was implanted with vacant shell as a control group. The facial nerves were obtained 2, 4, 6 months respectively after operation and the histological ultrastructural changes observed by electromicroscope.
  
  
  RESULTS
  In the control group, epineurium was continuous, there was slight pitting edema under the epineurium, and axonal myelin was loose. In the test groups, there was slight pitting edema under the epineurium, and axonal myelin sheath was loose at 4th month. Macrophage and regenerated fibers were found in the 80 Gy group and myelin sheath lamellar separation, regeneration of nerve in the 120 Gy dosage. The myelin sheath lamellar was separated and axonal myelin loose in the test group at 6th month. Myelin sheath amellar separation and edema under the epineurium were found in the group of 80 Gy and 120 Gy.
  
  
  CONCLUSIONS
  The ultrastructure of the facial nerve is damaged by the dosage of 40 Gy, 80 Gy brachytherapy with (125)I seeds. The higher dosage the nerve receives, the more serious the damage will be. Both of the epineurium and axonal myelin sheath are integral and continuous 6 months after operation with dosage of 120 Gy.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Peking University School, Beijing, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zuo
authors.forename: Tie-li
authors.initials: TL
authors.lastname: Song
authors.forename: Xiang-qun
authors.initials: XQ
authors.lastname: Ju
authors.forename: Lei
authors.initials: L
authors.lastname: Zheng
authors.forename: Zhi-gang
authors.initials: ZG
authors.lastname: Cai
authors.forename: Jian-guo
authors.initials: JG
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001918:Brachytherapy; D004307:Dose-Response Relationship, Radiation; D005154:Facial Nerve / Q000528:radiation effects* / Q000648:ultrastructure*; D005260:Female; D007457:Iodine Radioisotopes / Q000008:administration & dosage / Q000528:radiation effects*; D008297:Male; D011817:Rabbits; D011833:Radiation Injuries, Experimental / Q000473:pathology*; D011897:Random Allocation
chemical_list: D007457:Iodine Radioisotopes