Histology

 

Neurohistology

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Tox Path Specialists' laboratory is fully GLP-compliant and offers a wide range of histology services. TPS specializes in complex and detailed tissue trimming techniques, including the ability to harvest and process difficult tissues such as sympathetic ganglia. Additionally, TPS is an industry leader in thorough evaluations of nervous system tissues, including detailed brain and spinal cord sectioning schemes that frequently surpass industry standards.

TPS offers a variety of histology techniques, including standard paraffin embedding, resin/plastics embedding and ultra-thin sectioning, frozen sectioning for thick sections, over-sized slide production, and bone decalcification, among others. These techniques, used in conjunction with the multitude of immunohistochemistry (IHC) labeling and histochemistry staining methods detailed below, enable TPS to perform some of the most comprehensive nervous system investigations in the industry.

Several of TPS' commonly used IHC and histochemistry techniques are included below, but we are capable of much more than those listed here. Please contact us with any questions regarding other techniques, including immunohistochemistry method development.

Immunohistochemistry (IHC)

Ionized Calcium-Binding Adaptor Molecule 1 (IBA-1)

IBA-1 immunohistochemistry labels a protein that is unregulated by activated microglial cells and macrophages, making this a sensitive indicator of microglial activation in the central nervous system. As TPS, IBA-1 IHC is commonly performed to augment H&E staining, and can highlight reactions that are not otherwise visible.

Glial Fibrillary Acidic Protein (GFAP)

GFAP IHC labels an intermediate filament in astrocytes to provide a sensitive indicator of astrocytic responses to central nervous system damage. This labeling is commonly performed in addition to H&E and IBA-1 for a more complete understanding of glial responses.

Tyrosine Hydroxylase

(TH)

TH is a key enzyme in the production of dopamine and norepinephrine, and TH IHC labels neurons producing either neurotransmitter. This marker is typically used to target neurons in the pars compact region of the substantia nigra and/or post-ganglionic neurons of the sympathetic component of the nervous system.

Green Fluorescent Protein

(GFP)

For gene therapy vectors containing GFP, IHC on paraffin-embedded tissues can enable assessment of anti-GFP immunoreactivity as well as detailed morphologic evaluations.

Protein Gene Product 9.5

(PGP9.5)

This IHC technique identifies a protein specific to neurons and the neuroendocrine system. At TPS, PGP9.5 IHC is often performed on thick, frozen sections of footpad biopsies to enable intraepidermal nerve fiber density assessments.

Substance P

This neuropeptide is produced by sensory neurons and is associated with pain and inflammation. 

 

Histochemical Stains

Hematoxylin and Eosin

(H&E)

The gold standard for preclinical toxicology studies, H&E provides excellent nuclear and cytoplasmic detail for a variety of cell types. At TPS, H&E is used on nearly all studies, often in conjunction with IHC procedures.

Toluidine Blue

(TB)

TB allows for optimal assessments of myelin effects when used with resin/plastics-embedding techniques. At TPS, this stain is often utilized in order to provide extremely detailed sections of myelin in peripheral nerves.

Fluoro-Jade B

(FJB)

FJB is a sensitive and specific fluorescent stain used to detect neuronal necrosis. This stain is often used to detect necrosis in early-stage investigations that otherwise would not be observable by standard techniques.

Luxol Fast Blue

(LFB)

LFB is another histochemical stain (along with Toluidine Blue) that assists in detecting changes to myelin in the central nervous system.

Cresyl Violet

(CV)

Cresyl violet intensely stains neuronal Nissl substance, enabling detection of neuron cell bodies. This is a multi-purpose stain, and is frequently used at TPS when performing stereologic assessments of sympathetic and dorsal root ganglia.

Bielschowsky's Silver

(BS)

Bielschowsky's silver is a selective stain for neurofilamentous structures like axons. It is often used to help visualize axonal swelling and/or degeneration.

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