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Please consider the following guidelines to achieve the best histology.

Cassettes

We accept specimens submitted in fixative containers or tissue cassettes. We encourage specimen submissions in tissue cassettes, as you know your samples best and can ensure that areas of interest are captured. There is also a cost-saving if you submit in cassettes.

Cassette

  • Standard practice is to place the surface of interest down in the cassette, the tissue surface placed down in the cassette is then the first to be sectioned.
  • To prevent loss of small tissues during processing, use a biopsy cassette, biopsy bag, or wrap the specimen in filter paper in the cassette.
  • While multiple tissues may be placed in the same cassette, there are a few important considerations to ensure high quality.
  • Only tissues of the same consistency can be combined into the same cassette. For instance, liver and kidney have a similar consistency, but not liver and brain. Bones require decalcification and should never be combined with other tissue types.
  • Tissues must be cut thin before placing them in a cassette. This may require further trimming after they are fully fixed. The rule of thumb is that tissues in a cassette be no thicker than a nickel (0.2-0.5 cm).Tissues that are too thick or overcrowded in the cassette will not yield good results, as the specimens will not adequately fix, infiltrate with paraffin, section, or stain.
  • If your submission contains tissues that vary significantly in size (i.e., whole organs vs. biopsies) or consistency (i.e., soft tissues vs. bone or soft tissues vs. brain), sort similar cassettes into separate containers.
  • Label cassettes clearly and refrain from excessively long specimen IDs to ensures correct slide labeling.
  • Use only hard pencil (or specially purchased histology markers) when labeling cassettes. Never use pen, Sharpie marker, or scientific freezer-safe markers, as solvents used in tissue processing can dissolve this ink!
  • For your convenience we offer cassette printing services, as does the Animal Studies Core on the opposite end of campus.  https://www.med.unc.edu/ascore/

EmbeddingEmbedding

Tissue embedding is the careful orientation of processed tissues into a mold with paraffin wax, which provides a stabilization medium for microtome sectioning.

  • Our standard is to place one specimen per tissue block.
  • Additional tissues may be embedded together in the same block, size permitting. A maximum of 4 tissues can be embedded per block, although additional charges may incur.
  • If it is critical to capture a specific plane within a tissue, placing multiple tissues in the same block is not advised.
  • Please list any special embedding requests on the submission form.

Sectioning

We offer both paraffin and frozen sectioning to support your research needs. Paraffin sectioning is the cutting of thin tissue sections from a paraffin-embedded block using a microtome. Frozen sectioning is sectioning from specimens embedded in frozen OCT medium on a cryostat. For both processes, tissue sections are then mounted on a glass slide for downstream applications, such as histochemical staining, immunohistochemistry, immunofluorescence, or other molecular techniques.

Our experienced staff can capture specific structures in a multitude of tissue types. Through careful planning with our team, we can customize approaches to expertly capture your areas of interest.

Standard Sections:

  • 4um paraffin embedded sections, 5-15um frozen sections; one section per slide
  • Your experimental needs may require thicker or thinner tissue sections than the standard; generally, this is easily accommodated.
  • Due to the fragile nature of cell monolayer membranes, our standard practice places two serial sections from the same blockper slide to ensure an acceptable section is captured.
  • Placing multiple sections per slide is often cost-effective for projects utilizing RNAScope, ISH, and FISH. Your experimental needs may also require sections from different blocks on the same slide. Such customizations are usually possible. Contact our team for feasibility and pricing.Standard Sections
  • RNAase-free sectioning and tissue scrolls are also available.

RNA Free Image OneRNA Free Image Two

Sectioning Fees

  • One section per slide at set rates (available on infoporte.unc.edu)
  • Two sections per slide from the same block:

Up to 5 slides     no additional charge

6-10 slides           ½ hr tech time charge

11-15 slides        1 hr tech time charge

Extra dry or more complex tissues may require additional time

  • Multiple sections per slide from multiple blocks are charged the full slide rate per section. Additional tech time may be charged for sections that require further handling to fit on a slide.
  • There is a surcharge of $10.00 per block for RNAase free sectioning.