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Technical TipElectron Microscopy Sciences

Bone Marrow Biopsies

By Becky Scholes, HTL, MT (ASCP)


  1. Allow aspirate to clot in Petri dish.
  2. Transfer clot to specimen container filled with 10% buffered formalin.
  3. Process as usual.

Bone Core Fixation:

  1. Immediately fix in acetic formalin for a minimum of one hour.
  2. Fix overnight if brought in later than 2 hours before end of the work day.  Decalcify first thing in the morning.

Acetic Formalin

80% ethanol 900cc
Conc. Formalin 100cc
Acetic acid 50cc

Dilute RDO

Distilled water 1 part
RDO 3 parts


Bone Core Decalcifications:

  1. Place fixed core and label in a plastic cassette (RDO discolors metal). Decalcify in dilute RDO for 1 hour.  Do not leave overnight.
  2. Test for decalcification by gently checking for pliability.
  3. Rinse in running tap water for approximately 2 minutes.


  1. If biopsy came in afternoon, process with the rest of the specimens.
  2. If the biopsy is decalcified in the morning, hand process in 120cc plastic specimen cups, 15 minutes in each container, starting with 70% ethanol or speed process through processor, 15 minutes each station with heat and vacuum, starting with the first dehydrant station.


  1. Cut both aspirate and bone cores at 2 microns.
  2. Place 3 levels on one slide.  Cut an extra slide of the last level and set aside on the back of the water bath in case a special stain is requested.


  1. Hematoxylin approximately 5 minutes.  Bone core 1 minute (check under the microscope before counterstaining).
  2. Eosin for 10 dips, dehydrate, clear and coverslip.


Over decalcification will result in poor or indifferent histological detail and staining characteristics.  Less than one hour is usually not sufficient.

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