What is Histology? Histology is a science dealing with the structure of cells and their formation into tissues and organs. Histotechnology centers on the detection of tissue abnormalities and the treatment for the diseases causing the abnormalities. Many dyes and chemicals are used in histology, and it is important to know their composition, how they act, and how they react with each other. With this knowledge, combined with an understanding of tissue composition, the histotechnologist treats the tissue with these chemicals and dyes. The chemical reactions produce colors, which make it possible to distinguish tissue structures. In the modern histology lab immunological and molecular (DNA) techniques are frequently utilized to provide accurate tumor identification which will aid the clinician in selecting a mode of therapy that offers that greatest probability of cure.

Occupational Description: Histotechnicians (HTs) and histotechnologists (HTLs) are members of a laboratory team who employ histologic technology to diagnose diseases, to conduct research, or to instruct others in the science. Histotechnologists play a fundamental role in the allied health profession. A histotechnologist will prepare very thin slices of human, animal or plant tissue for microscopic examination. This is an important part of the intricate process of scientific investigation used in establishing and confirming patient diagnosis. Because of the histotechnologist’s skillful application of sophisticated laboratory techniques, the seemingly invisible world of tissue structure becomes visible under a microscope. The tasks performed by the histotechnologist require patience, mechanical ability, knowledge of biology, immunology, molecular biology, anatomy and chemistry. It requires five basic steps, each an integral part of the histotechnologist’s job.

	Grossing & Fixation – Tissue specimens taken from routine surgical cases, autopsies, or other scientific investigations are examined, described and trimmed to proper size. This process is referred to as “grossing the specimen”. The resulting specimens are preserved by placing them in solutions designed to prevent decomposition. This is known as fixation.
	Processing – water is removed from the tissue and replaced by melted paraffin wax. The wax infiltrates the tissue and provides the necessary support when cutting the tissue into thin slices which will eventually be examined under a microscope.
	Embedding – Before the wax permeated tissue can be cut it is placed in a larger wax block for additional holding support during sectioning.
	Sectioning – The tissue is mounted onto a delicate instrument called a microtome. An extremely sharp knife is used to cut sections of the tissue embedded in the wax block. These sections are cut one after another to form a ribbon, which is floated on warm water to soften and flatten tissue sections. These sections are then placed on microscopic slides and stored for future procedures.
	Staining – Staining causes tissue components to change colors when brought into contact with different chemicals. In addition to dyes, antibodies are reacted with tissues to identify specific tumor cell lines with a method called Immunohistochemistry. This technique is critical to guiding the patient’s physician in selecting the most effective tumor treatment. DNA probes are also applied to tissue sections to identify the presence of bacterial and viral infections and some tumors. When staining is completed, the tissue section is ready for examination under a microscope by a pathologist or other scientific investigator. Without specialized staining techniques, many tissue components would remain invisible.

Immunohistochemistry: The field of Histotechnique has evolved to include more than dye staining to demonstrate tissue structures.  Methods such as, enzyme histochemistry to localize enzymes in tissue and Immunohistochemistry (IHC) to demonstrate antigen-antibody reactions, are also very important diagnostic tools for histopathology.

A Qualification in Immunohistochemistry (QIHC) has been established by the American Society for Clinical Pathology (ASCP) as a sub-specialty category of expertise in the field of Histotechnology.  Those experienced in Immunohistochemistry can take an all practical exam and obtain a "Qualification in Immunohistochemistry" which recognizes their expertise in Immunohistochemistry (IHC).

A committee through the National Society for Histotechnology (NSH), as a resource exchange for those working in the field of Immunohistochemistry, has been formed.  The NSH committee is called the Immunohistochemistry Resource Group (IHCRG).  This group connects all it's over 300 members from all over the world, so that they can share expertise and resources in Immunohistochemistry.  The IHCRG maintains a web site packed full of resourceful information useful to those working in the IHC field.  The web site address is:  www.ihcrg.org

Hours and Earnings: Most HTs and HTLs work forty hours a week. Since hospitals are open twenty-four hours a day, seven days a week, HTs and HTLs may work nights or rotating shifts. They may work weekends and holidays and have days off in the middle of the week. The earnings of HTs and HTLs vary with their training, the employer, and the location of the hospital. In general, HTs and HTLs in large cities and on the East Coast get the highest pay.

Certification, Qualification and Education: Certification as a Histotechnician or a Histotechnologist is governed by the Board of Registry through the ASCP. The BOR certifies individuals upon completion of academic prerequisites, clinical laboratory education or experience, and successful performance on an examination.

The certification examination consists of two parts: practical and written for both the technician and technologist. After passing the examination, technicians may use the initials HT(ASCP) – which stand for histotechnician certified by the American Society of Clinical Pathologists –after their name. Histotechnologists may use the initials HTL(ASCP).

        A. Certification requirements:

Histotechnician (HT) – to be eligible for this examination category, an applicant must satisfy the requirements of a least one of the following qualification routes:

1.   Successful completion of a NAACLS accredited Histotechnician Program.

2.   Associate degree or at leat 60 semester hours (90 quarter hours) of academic credit from a regionally accredited college/university with combination of 12 semester hours (18 quarter hours) of biology and chemistry, and one year full time acceptable experience in histopathology within the last ten years under the supervision of a pathologist (certified by the American Board of Pathology in Anatomic Pathology, or eligible), or an appropriately certified medical scientist.

3.   High school graduation (or equivalent and two years full time acceptable experience in histopathology, within the last ten years, under the supervision of a pathologist (certified by the American Board of Pathology in Anatomic Pathology, or eligible), or an appropriately certified medical scientist.

As of January 2005, Route 3 will be discontinued.
 

Histotechnologist (HTL) - to be eligible for this examination category, an applicant must satisfy the requirements of at least one of the following qualification routes.

1.  Baccalaureate degree from a regionally accredited college/university with a combination of 30 semester hours (45 quarter hours) of biology and chemistry, and one year full time acceptable experience in a histopathology laboratory within the last ten years, under the supervision of a pathologist (certified by the American Board of Pathology in Anatomic Pathology, or eligible), or an appropriately certified medical scientist.

2.  Baccalaureate degree from a regionally accredited college/university including the above course requirements, and successful completion of a NAACLS accredited Histology Technician or Histotechnology program.

 
Applications for certification can be obtained from:       

                                    ASCP, Board of Registry
                                    PO BOX 12277
                                    Chicago, IL 60612
                                    800-621-4142
 

B. Qualification:

The ASCP offers a qualification in Immunohistochemistry which recognizes completion of the eligibility requirements and successful completion of the work sample project. The qualification may be revalidated every five years with documentation of acceptable continuing education.
 

The purpose of this qualification is to assess the competency of examinees in the technical application of clinically relevant immunohistochemical techniques.
 

C. Employment:

Most histotechnicians and histotechnologists work in hospitals, medical clinics, and universities. Opportunities also exist in government agencies (like the Food & Drug Administration, and the Environmental Protection Agency). Some histotechnicians and histotechnologists work in the laboratories of firms that produce or process chemical, pharmaceutical, and household products, and medical devices. Laboratory tests are essential in medical treatment, and the volume of testing will continue to grow. Population growth and the large increase in the number of elderly, who are subject to illness, will increase the demand for medical care, staff and resources.

For full details on how to join this dynamic profession, please refer to the list of accredited training programs at www.nsh.org

National Society for Histotechnology
10320 Little Patuxent Parkway
Suite 804
Columbia, MD 21044
Telephone: 443-535-4066
Fax: 443-535-4055

Last updated: May 2002