New York Medical College

Research

Core Histology Laboratory

Department of Pathology Core Histology Laboratory

 

Histology Services Guidelines

For researchers without easy access to histology equipment or the services of a histotechnologist, the Histopathology Core Lab accepts fixed wet tissue specimens as well as frozen tissue samples.  Wet samples are processed on an automated tissue processor.  The processing protocol is adjusted to match the size of the tissue specimen submitted.

Touch preps can be made from fresh or frozen tissues.  We can provide paraffin sections and frozen sections in addition to or in place of solid tissue samples.  Sections can be prepared on standard charged, and they may be stained with Hematoxylin & Eosin (H&E) or left unstained.  Thick sections, scrolls or a ribbon of serial sections may also be provided.  Our histology SOPs strive to maintain the highest possible specimen quality and minimize the possibility of cross-contamination.  Some of these services incur a small additional charge.  Please refer to our pricing structure or contact us for details.

For submitting tissue samples please review our tissue submission guidelines:

Specimens for FFPE (formalin-fixed paraffin embedded)

  • All specimens submitted for paraffin processing should be fixed in 10% neutral buffered formalin (NBF).
  • Specimens will need to be fixed in NBF for a minimum of 24 hrs. (longer for larger specimens) for adequate fixation before we can process the tissue.
  • The amount of fixative should be at least 10 to 20 times the volume of the specimen in order to ensure optimal fixation.
  • Specimens fixed in freshly prepared paraformaldehyde should be rinsed in PBS prior to submission. A Histology Requisition Form must be completed that identifies each specimen being submitted.
  • All identifying data must be completed.
  • The specimen identifiers on each specimen submitted must match the identifiers used on the drop off form. All specimen containers must bear a clear label identifying the contents.
  • Each specimen (organ or lesion etc.) should be in its own container with a unique specimen identifier.
  • We discourage the use of non-unique ID number such as using 1,2,3,4, etc.  This can lead to problems differentiating between customers specimens.  Also bear in mind that the ID should not be too long as it needs to fit on the front of a standard tissue cassette.
  • Please differentiate the ID number from other extraneous information on the specimen container to eliminate any confusion.
  • In addition to the laboratory identifiers, a Core Lab # will be assigned for each job submitted.
  • Containers of formalin must also bear a warning label indicating that formaldehyde is a known carcinogen.

 

Frozen Sections

There are two kinds of frozen tissue that are used for immunocytochemistry: Fresh frozen or fixed tissue.  The fresh frozen tissue should be frozen immediately after the animal is dissected.  The fixed frozen tissue should be fixed first then frozen.

Preparation of Tissue for Fresh Frozen Sections

  • Before you dissect the animal get one special container filled with liquid nitrogen and another container filled with some dry ice.
  • Label base mold and partially fill the mold with OCT or TFM (Tissue Freezing Medium).
  • Remove desired tissue and place in cold PBS and wash out the blood.
  • Transfer tissue to a clean petri dish and use the kimwipes to absorb the PBS on the tissue surface.
  • Place tissue in pre-labeled base molds filled with OCT/TFM. Try to arrange tissue flat in OCT/TFM near the bottom so tissue is easily exposed when sections are cut.
  • Use forceps to hold base mold edge and place the base mold into the surface of the liquid nitrogen and just let bottom of base mold to touch the surface of the nitrogen. Hold until the tissue solidifies (around 30 seconds). Note: If block is left in too long, it may crack.
  • Remove tissue from liquid nitrogen and place blocked tissue on dry ice. (Tissue may be kept in plastic container or plastic bags.)
  • Store frozen tissue block in -80°C freezer until sectioning.

Preparation of Tissue for Fixed Frozen Sections

  • Remove desired tissue and place in cold PBS and wash out blood.
  • Place tissue into fixative and fix for 2-4 hours or overnight depend on the tissue sizes. The volume should be 10 to 20 times of the tissue.
  • Wash with cold PBS 1 min.
  • Wash with PBS 10 or 20 min 3X. During wash steps get one special container fill with liquid nitrogen and another container fill with same dry ice. Label base mold and partially fill the mold with OCT/TFM.
  • Transfer tissue to a clean petri dish and use the kimwipes to absorb the PBS on the tissue surface.
  • Place tissue in pre-labeled base molds filled with OCT/TFM. Try to arrange tissue flat in OCT/TFM near the bottom so tissue is easily exposed when sections are cut.
  • Use forceps to hold base mold edge and place the base mold into the surface of the liquid nitrogen and just let bottom of base mold to touch the surface of the nitrogen. Hold until the tissue solidifies (around 30 seconds). Note: If block is left in too long, it may crack.
  • Remove tissue from liquid nitrogen and place blocked tissue on dry ice. (Tissue may be kept in plastic container or plastic bags.)
  • Store frozen tissue block in -80°C freezer until sectioning.

 

In another way: after fixation of tissue, wash with PBS 10 min or 20 min 3X. Then put tissue into 15% sucrose made in PBS for several hours or overnight, then into 30% sucrose in PBS and leave on a rotator until the tissue sinks (this may take a day or two depending on size of tissue). Label base mold and fill the mold with OCT/TFM. Transfer tissue to a clean petri dish and use kimwipes to absorb excess sucrose. Place tissue in pre-labeled base molds filled with OCT/TFM. Try to arrange tissue flat in OCT/TFM near the bottom so tissue is easily exposed when cutting sections. Place block on dry ice. Store tissue blocks in -80oC freezer until ready to section.