Standard Tissue Collection for Immersion Fixation

Tissue trimming (prior to fixation)

  • Most fixatives penetrate very slowly. No fixative will penetrate more than 2-3 mm of solid tissue in 24 hours. Most specimens should be no more than 4 mm for good fixation, but 3 mm is preferred.
  • If you are working with whole brains, large tumors, or large organ pieces, standard-sized tissue pieces may not be big enough for your work. If you are unsure, we can help you decide how large your tissue should be.
  • If you cut sections thicker than 4 mm, do not use standard-sized cassettes. Standard-sized cassettes will squeeze larger samples causing under-processing. If you need larger cassettes, please contact our lab about where to buy them.

Tissue fixation

  • Researchers are responsible for their choice of fixative and fixation time. If you have questions about fixation, please contact our lab.
  • Be sure to follow the standard tissue submission procedure. Always submit (in person or via mail) samples in 70% ethanol, along with a hard copy of the online submission form.

Standard Tissue Submission Procedure for Immersion Fixation

Place the tissue in a labeled cassette

  • Separate tissue samples of different sizes into different cassettes. If you submit tissues of different sizes together in the same cassettes, we will have to add on a charge for separating them out into individual cassettes.
  • Use a #1 pencil to label the cassettes. If you label the cassettes with a sharpie, the labels will come off during processing and we will have no way to distinguish your samples from each other. NOTE: #2 pencils wipe off more easily, so please label using #1 pencils.

Completely fill out an online submission form

  • Include all basic information, tissue information, any special instructions while completing the online submission form.

We will call or email you when your work is complete

  • Please include both types of contact information on the submission form.
  • Any emails that we send to you will have “Histology Work” as the subject header.

Tissue Morphology

  • Fix tissue in appropriate fixative for paraffin-embedded tissue
  • After fixation, tissue should be stored in 70% ETOH, except for brain, spinal cord, or any fatty/lipid-rich organ, which should be stored in PBS at 4°C.


  • Check the specifications for the antibodies you will be using and request the appropriate type of embedding.
  • If you have any questions about Immunohistochemistry (or immunofluorescence), please contact Dr. Andy Ambrus at

Frozen Sectioning

  • If you are submitting your frozen tissue in pre-made blocks, be sure to embed all the sections in the same orientation, and let us know in which plane you want them sectioned.

If you are beginning a new project, we would be glad to speak with you about any specifics before you collect any tissue. We strongly recommend consulting with us on new projects so that you will not waste time or animals by making avoidable mistakes.

If you have any questions, contact us at:
Tel: 979.845.9486 [VMS Bldg. (#507), Room 271]
Tel: 979.862.4666 [VMS Bldg. (#507), Room 252]