Trimming Tissues

Trimming Tissues

Trimming Tissues

Use a sharp blade such as this one, which has a handle with replaceable blades. Handles and blades are available from vendors of histology and pathology supplies.

Tissues must be trimmed to a thickness that will allow them to be completely permeated with paraffin, and to provide the orientation needed. We suggest "thick as a nickel" as a thumb rule. Some mouse organs are small enough that they are best embedded whole.


If there is an area of particular interest, such as a tumor, in the specimen, trim the tissue so that the area of interest is near one surface of the specimen, and place that surface down in the cassette.

Be sure to let the histotechs know if the area of interest is very small to ensure that it is not lost or missed. Be advised that it is very difficult to trim and embed tissues so precisely that it can be determined before sectioning which sections will contain such areas. In such cases it is advisable to request serial sectioning and to save all sections until you're certain you've obtained the information you need. Blocks can always be cut deeper, but discarded sections are gone forever.

Don't place too many tissues in the cassette. Overcrowding can inhibit proper processing, and it isn't possible to get that many tissues positioned in the block for good sectioning anyway. This one should have about 1/2 or 2/3 of the amount of tissue shown.

As a general rule, place tissues of similar consistency together. For example, don't place tough tissues such as skin in the same cassette as soft tissues such as spleen or brain. If the tissues vary greatly in consistency, they may not all section well.

If the tissue is very small, biopsy pads can be used to help prevent the specimen from being lost. Biopsy cassettes with fine screens also are available. Biopsy pads also can be used to prevent samples of skin and hollow organs from curling during fixation, but care must be taken not to compress or distort the tissue.

In general, biopsy pads should not be used with larger tissue samples. However, they can be used to maintain orientation or positioning of trimmed samples, as distortion is of less concern with fixed solid tissues. (See the examples on the Special processing & embedding page.)

Additional News and Announcements

  • IRB Continuing Training Requirement for 2015

    ​UAB IRB policy requires continuing training once in every three year period for key personnel involved in human subjects research.  The UAB Office of the IRB has worked with the CITI Program to create different continuing training courses for (1) Biomedical and (2) Social/Behavioral/Educational researchers.  UAB personnel may complete either of these courses to meet continuing training requirements.  Both courses require investigators to complete three required modules and three of six elective modules. 
    Key personnel who completed their initial human subjects training before January 1, 2015 are required to complete one of the continuing training courses prior to December 31, 2015.  This continuing training will be valid for the 2015-2017 period.
    Additional information, including step by step instructions for registering, can be found on the OIRB website:  Continuing IRB Training.
    If you have questions about IRB training requirements, please contact the Office of the IRB at 934-3789.
    Posted by Office of the Institutional Review Board for Human Use | 10/09/15
  • New UAB Institutional Core Facility Program Launched

    The UAB Office of the Vice President for Research and Economic Development (OVPRED) announces the launch of the UAB Institutional Core Facility Program (ICFP), created to promote the development and operation of outstanding Core Facilities that can serve the needs of UAB investigators.
    Posted by Office of the Vice President for Research and Economic Development | 10/02/15
  • White Paper Solicitation for Major New Alabama Research Initiatives

    ​Alabama EPSCoR (ALEPSCoR) would like to solicit White Papers for major new research initiatives in targeted areas where Alabama can achieve national competitiveness and leadership. The goal of these targeted research initiatives will be to create the necessary State-wide research and education infrastructure to foster ground-breaking technology innovations resulting in substantial federal grant funding and intellectual property development that will create jobs for the State. The desired outcome of this white paper solicitation is to select one or two major new research initiatives for future investment and large scale multi-institutional proposal submissions.
    Posted by Office of the Vice President for Research and Economic Development | 09/16/15
  • Dr. Rakesh Patel, Ph.D. announced as new Director for the Center for Free Radical Biology

    Dr. Selwyn Vickers, M.D., F.A.C.S, Senior Vice President for Medicine and Dean, School of Medicine, and Dr. Richard Marchase, Ph.D., Vice President for Research and Economic Development, are pleased to announce that Rakesh Patel, Ph.D., will be the new director of the Center for Free Radical Biology (CFRB) from October 1, 2015, when Dr. Victor Darley-Usmar, Ph.D. steps down after serving as Director since 2006.
    Posted by Office of the Vice President for Research and Economic Development | 09/10/15
  • Change in State Law Regarding Age of Consent

    On May 7, 2015, Governor Bentley signed into law Act 2015-167, which lowered the age of consent to 18 years old (previously 19 years) for IRB-approved research conducted by an accredited college or university. This means that 18 year olds may now consent for themselves to participate in research conducted at UAB under IRB approval. The IRB has updated most of its forms with this information and will continue to revise policies and procedures to recognize this change in the law. The revised forms must be used for all submissions received in the OIRB after September 1, 2015.
    Posted by Office of the Institutional Review Board for Human Use | 06/26/15
  • IRB Form Changes - June 2015

    UAB IRB forms have been revised as of June, 2015. New versions of these forms will be required for all submissions received after September 1, 2015. These include: Human Subjects Protocol, Investigator's Progress Report, Sample Consent Form, Checklists for new submissions for both full and expedited reviews, Checklists for renewal submissions for both full and expedited reviews.
    Posted by Office of the Institutional Review Board for Human Use | 06/26/15
  • Confidential Disclosure Agreement Templates Updated

    UAB’s template confidential disclosure agreements have been updated and are available at the OSP Confidentiality Disclosure Agreement (CDA) webpage. The following confidential disclosure agreement (CDA) templates are available:

    Mutual Confidential Disclosure Agreement (Company and UAB disclosing confidential information);

    Unilateral Confidential Disclosure Agreement (Company Disclosing to UAB); and

    Unilateral Confidential Disclosure Agreement (UAB Disclosing to Company)

    Please use, and encourage the contracting party to use, the appropriate UAB template CDA. If the contracting party can agree to the terms of one of UAB’s template CDAs, UAB will sign the agreement without further routing and review, resulting in a more expeditious process.

    Please forward any questions regarding the CDA process, or UAB’s template CDAs to

    Posted by Office of Sponsored Programs | 06/22/15
  • Policy Update: Definition of a Principal Investigator

    Effective May 18, 2015 UAB’s Definition of a Principal Investigator policy is modified with regard to UAB employees in the 02 (Full-time Temporary) employment status or other UAB employment categories. See the full policy at the link or via the UAB Policies & Procedures Library.

    Case-by-case inquiries should be addressed to
    Posted by Office of Sponsored Programs | 06/01/15
  • Expired Form FDA 1572 continued use approved

    ​On April 30, 2015 the Form FDA 1572 on the FDA website at is expired.

    The FDA is in the process of updating and posting a new Form FDA 1572. Even though it is expired, the FDA approved continued use of the current form.

    We will monitor the FDA website and will post notice of the new form's release, when available.

    Posted by Office of the Institutional Review Board for Human Use | 05/06/15
  • Additional OSP Dropbox Enhancements

    The Office of Sponsored Programs is pleased to announce additional enhancements to the OSP dropbox for electronic SF424 grant applications to The link to access the OSP dropbox is OSP Drop Box for Electronic Submissions to . The revised OSP dropbox user guide can be found at OSP Dropbox Quick Submission Guide. New enhancements to the dropbox include:

    • The attribute page has been modified to prompt the user to create a record and then upload the files. When the proposal record is created the attribute page is refreshed with the comment “Submit Successful*” with a footnote to continue to upload files (“*Please continue on to the Upload Files section and attach your proposal documents”).

    • Once the proposal record is created, the Upload file tab is now used to upload the proposal documents.

    • The upload file history can now be viewed using the “File History” section.  This allows users to verify that the upload was successful.

    If you have any questions regarding the new OSP dropbox functionality, please contact your OSP federal officer or

    Posted by Office of Sponsored Programs | 04/21/15
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