Histoteknoloji

GLP Compliance and Technical Standardization in Histotechnology

Histotechnology is a fundamental discipline at the heart of preclinical toxicity and efficacy studies, enabling the preparation of tissue samples for microscopic evaluation. This multi-step process encompasses stages ranging from fixation to tissue tracking, paraffin embedding, sectioning, and staining. The acceptance of the resulting histopathological data by regulatory authorities (OECD, FDA, EMA) depends not only on an experienced pathology team but also on a histotechnology process that is conducted in accordance with Good Laboratory Practice (GLP) principles and is fully standardized and documented.

Nano-Tox Laboratory Services: Our histotechnology laboratory, operating within our Pathology Testing Unit, is structured to fully meet this requirement. All our procedures are supported by validated equipment, approved Standard Operating Procedures (SOPs), and continuous quality control mechanisms.

Fixation and Tissue Tracking: The Foundations of Reproducibility

Fixation is the first and most critical step in the histotechnology process. To halt cellular autolysis, preserve morphological structure, and stabilize antigenicity, fixation solutions and times optimized for each tissue type are meticulously applied in our laboratory. Fresh tissue is time-stamped at the time of necropsy and immediately subjected to fixation. Since this step directly affects the sensitivity and specificity of all subsequent immunohistochemical and histochemical staining, no deviations from the protocol are permitted.

Following fixation, fully automated, closed-loop tissue processing systems are used to eliminate the variability that manual methods may introduce. The dehydration, clearing, and paraffin infiltration stages are carried out according to predefined and validated programs for each study. The shelf life and rotation frequency of all reagents are controlled via Standard Operating Procedures (SOPs). At the end of the process, each paraffin block is labeled with a unique sample identification number, incorporated into a GLP-compliant chain of custody, and prepared for long-term archiving.

Precision in Microtomy and Staining Procedures

The process of obtaining sections from paraffin-embedded tissue blocks (microtomy) is performed by our certified histotechnologists using calibrated rotary microtomes. Sections, typically 3–5 microns thick, are mounted on positively charged slides after being spread in a temperature-controlled water bath. At this stage, consistency in section thickness and the prevention of artifact formation are critical to the quality of the histopathological evaluation.

At the Nano-Tox Pathology Testing Unit, routine Hematoxylin & Eosin (H&E) stains are performed on automated staining platforms using validated protocols. Positive control slides included in every staining cycle enable continuous monitoring of staining quality and ensure consistency from batch to batch.

Beyond H&E staining, specialized histochemical stains (Masson’s Trichrome, Sirius Red, PAS, Congo Red, etc.) are also offered at the same level of standardization to identify specific cellular components and pathological deposits.

Immunohistochemistry (IHC) and Regulatory Compliance

In studies requiring the in situ detection and localization of specific protein expressions, immunohistochemistry (IHC) is one of our laboratory’s core areas of expertise. Automated IHC staining instruments are used to eliminate variability that may arise from manual procedures. Optimized incubation times, antigen retrieval methods, and appropriate detection systems have been established for each primary antibody, and appropriate positive and negative tissue controls are stained concurrently with each assay. This approach confirms the specificity of the signal obtained and ensures the level of scientific evidence required for regulatory submissions.

As a result, all histotechnology processes conducted in Nano-Tox laboratories are supported by a comprehensive documentation and quality control chain, from the raw tissue sample to the archived digital or physical slide. If you are seeking a technically flawless and reliable partner for the pathology component of your preclinical studies—one that is fully compliant with regulatory standards—the Nano-Tox Pathology Testing Unit is ready to serve you in this regard.