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Histology Unit

Researcher wearing blue latex gloves and handling eye specimens

Facilities and equipment

The National Eye Institute's Histology Unit provides expertise and up-to-date technical services for histological (under a light microscope or electron microscope) and cytological analyses for all of NEI and other NIH scientists. Additionally, the NEI Histology Unit provides services for the pathological diagnosis of ocular diseases for clinicians. This data can be made available in a visual or quantitative format.


The Unit staff provides technical assistance in the development and optimization of histopathological and morphometric techniques, including the following:

Sample preparation and sectioning

  • Fixation of cells, tissues and organs
  • Grossing tissues and organs, particularly the eyes (human and animal)
  • Embedding frozen tissues or organs in OCT (optimal cutting temperature)
  • Embedding samples in methacrylate or paraffin for light microscopy
  • Embedding samples in resin for electron microscopy
  • Sectioning frozen samples with a cryostat
  • Sectioning of embedded samples with a microtome or ultramicrotome

Slide processing

  • Routine histological stains such as H&E or PAS II and stains such as Gram stains, AFB, silver, etc.
  • Immunostaining of human cells, tissues and organs with enzyme histochemistry (acid phosphatase, alkaline phosphatase, HRP, ABC avidin-biotin-complex)

Last updated: September 29, 2022