Dissection Manual for the Mouse Temporal Bone, Fourth Edition

Details

• Personal Author:
  Bohne BA ; Harding GW
• Description:
  The membranous labyrinth containing the organ of Corti is housed within the bony labyrinth of the temporal bone. In order to collect quantitative data (e.g., number of missing hair cells), it is best to examine the organ of Corti as a 'surface' or 'flat' preparation. One technique for making surface preparations involves dissecting the cochlea in liquid, removing segments of the organ of Corti and mounting them on microscope slides (e.g., Engström et al., 1966; Norris et al., 1977; Ohlemiller et al., 1999). After fixation, the cochlea is immersed in buffer or ethanol. The cochlear bone is broken away with hooks and forceps. The spiral ligament, Reissner's membrane and the tectorial membrane are removed from the specimen with small forceps and scissors. Using a small knife, the organ of Corti is divided into short segments which are then carefully separated from the modiolus. The organ-of-Corti segments are then mounted on glass slides in a liquid medium such as glycerin, cover slipped and examined microscopically. The advantage of this 'wet' surface preparation technique is that the organ of Corti can be examined microscopically on the day of specimen fixation. Disadvantages of this technique include: 1) Preparation artifacts such as distortion or loss of sensory and supporting cells often occur in portions of the organ of Corti because the sensory epithelium is dissected while it is immersed in a liquid medium. Quantitative data cannot be collected when segments have been damaged or destroyed; and 2) The soft tissue of the cochlea deteriorate if the specimen is left in buffer or alcohol for more than a few days. Dissected segments of the organ of Corti that are mounted in liquid also deteriorate within a few weeks. Another way in which to obtain surface preparations of the organ of Corti is to embed the temporal bone in plastic after fixation, then dissect the specimen after the plastic polymerizes. Bohne and Harding (1997) and Bohne et al. (2001) described the steps required for fixing, dehydrating and embedding the mouse temporal bone in plastic. The advantages of this 'plastic-embedded' surface preparation technique are: 1) Dissection artifacts are rare; and 2) Plastic-embedded cochleae and organ-of-Corti segments are stable and can be dissected and evaluated years after fixation and embedding. The disadvantage of this technique is that more time is required between specimen fixation and evaluation. Because of the time required for plastic polymerization, the earliest that a plastic-embedded cochlea can be examined microscopically is approximately six days after specimen fixation. [Description provided by NIOSH]
• Subjects:
  Ear Histology Laboratories Microbiology Occupational Health Safety Sense Organs
• Keywords:
  Auditory System Ears Laboratory Animals Laboratory Techniques Microscopic Analysis
• Publisher:
  Washington University School of Medicine
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Handbooks
• Place as Subject:
  Missouri ; OSHA Region 7
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-35
• NIOSHTIC Number:
  nn:20055535
• Citation:
  St. Louis, MO: Washington University School of Medicine, 2011 Sep; :1-35
• Federal Fiscal Year:
  2011
• NORA Priority Area:
  Manufacturing ; Wholesale and Retail Trade
• Performing Organization:
  Washington University, St. Louis
• Peer Reviewed:
  False
• Start Date:
  20000401
• Source Full Name:
  Dissection manual for the mouse temporal bone, fourth edition
• End Date:
  20130914
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:5fdc2c82267e61fd1e8267a9d4759489709a888bb7f9e997552c587022e7b8be3d35498f71915c4699c3ea77e8a98c07491a8821da03cca054f0d33767dbe564
• Download URL:
  https://stacks.cdc.gov/view/cdc/213365/cdc_213365_DS1.pdf
• File Type:
  [PDF - 1.22 MB ]