Histology Laboratory

Histology Submission Instructions – Formalin Fixed Tissues

Fixation is the single most important preparative histological technique. The purpose of fixation is to preserve tissues permanently in as life-like a state as possible. Fixation should be carried out as soon as possible after removal of the tissues. Poor fixation cannot be remedied at any later stage and is the source of most of the problems we see in our lab. In our experience, under-fixation is a much greater problem than over-fixation. If the tissue is under-fixed, exposure to alcohols can dramatically alter antigen structure, modify morphology, and result in the loss of up to 40% of the protein content of the tissue. These effects are permanent and irretrievable


  • Tissue cassettes.
  • Closed container with adequate fixative.
  • Number two pencil or Histology pens.
  • Properly trimmed tissues.
  • Pathology Research Resources Histology Laboratory Submission form.


1. Label side and top of cassette with a #2 pencil or histology pen (allow drying before place cassette in formalin). Please write legibly.

2. Tissues submitted should not be more than 3 mm thick. Take as reference a nickel for thickness and a post stamp for size.

3. Handle all tissues gently; grasp samples at the edges. Place tissues in labeled cassettes and be certain that the cassettes are securely closed.

4. Do not place more than three tissue samples per cassette.

5. Tiny pieces must be wrapped in lens papers or placed between sponges.

6. Place cassettes in fixative as soon as possible, Ensure container is properly closed and labeled containing: Name of fixative, time of collection and number of cassettes. If tissues are submitted without cassettes, do not place them in conical tubes or narrow mouth containers.

7. Tissue cassettes should be fully submerged in fixative to prevent partial fixation which will affect the quality of the sections. The ratio of fixative to tissue (volume: tissue) should be 10:1.

8. Complete the Pathology Research Resources submission form.

9. Discuss your needs with the histotechnologist and/or provide a written protocols specifying

  • Type of tissue submitted
  • Orientation of tissue
  • Thickness of the sections
  • Number of sections per slide
  • Number of slides per block
  • Amount of levels or series
  • Special instructions


  • Specimens smaller than 1mm. may not survive processing due to cell shrinking and the agitation and vacuum pressure involved during processing.
  • Any tissues that contains bone or calcified tissue require special handling.

Questions? Please visit our lab located at RSMB 7th floor, room 7128 or call us atl 305-243-3824