Written by: Therese C. Oyales
Edited and Reviewed byDr. Reuben J C. Los Baños, Ph.D.
A histopathologist diagnoses diseases after careful examination of a tissue sample. They track the disease’s progression by looking for abnormal changes in the cells. Cancer cells, infections, and inflammations are the kinds of abnormalities histopathologists check for.
Histopathologists do not work alone. They work in a multidisciplinary team. This team documents, processes, or examines the patient’s samples (biopsy). They also meet with other physicians to discuss the findings. Some healthcare professionals they work with include:
- Laboratory staff
- Nurses
- Molecular scientists
- Mortuary staff
- Surgeons
- Oncologists
- Radiologists
- Forensic medicine scientist
These healthcare workers discuss each patient’s condition and create a treatment plan that suits their individual needs. Once treatment has started, they will monitor its effectiveness. They will continue the medication or therapy if the histopathologist notices signs of healing.
The field of histopathology is not limited to samples from living people. A forensic histopathologist determines the cause of death of individuals at crime scenes. Generally, they do not perform autopsies. They do microscopic analyses on tissues from internal organs.
Tools of the trade
Did you know that the microscope is the most essential tool in a histopathology laboratory? It allows the histopathologist to view organisms that are too small to see with the naked eye. It reveals the cells’ detailed structures and the presence of abnormalities.
Some equipment used for tissue preparation are:
- Microtome
A microtome slices the block of embedded tissue into very thin sections. It is a precise and accurate instrument that creates “ribbons” for easy sequencing of the sections. Different microtomes are used for paraffin, plastic, and frozen sections due to the material’s toughness.
- Paraffin wax bath
The histopathologist manipulates the sections using a paraffin wax bath to arrange them into the desired orientation and location. They transfer the sections into glass slides using the hot distilled water from the bath.
- Automatic Tissue Processor
An automatic tissue processor prepares tissues for the histopathologist. It can fix, dehydrate, clear, and infiltrate the specimen.
- Embedding Cassettes
Histopathologists use embedding cassettes to secure the tissue specimens for storage, processing, and embedding.
Who is the father of tissue study?
Marie-François Xavier Bichat is regarded as the father of tissue study. He was a French anatomist, pathologist, and physiologist whose contributions led to the establishment of the scientific study of tissues.
Bichat was born on November 14, 1771, in Bresse, France. His family supported his interest in science and medicine. His father, Jean Baptiste Bichat, was a physician at Montpellier and was a great inspiration to the young boy.
He started his medical journey at Lyon, where Marc-Antoine Petit, a chief surgeon at the Hôtel Dieu, became his mentor. In 1793, he studied under a surgeon and anatomist called Pierre-Joseph Desault. After his teacher passed, he continued doing research and publishing books on his own.
Contributions
- Pioneer of histology. Bichat was the first to study tissues. He proposed that organs are made up of groups of tissues that share similar structure and function. He discovered the organizational level between organs and cells, and these are tissues.
- Correlation between structure and function. Bichat established that the structure of cells and tissues relates to their function. Their arrangement and shape are tied to their specific roles in the body.
- Classification of tissues. Bichat distinguished 21 kinds of tissues based on their specific characteristics. He analyzed the different combinations and roles of each tissue kind.
Publications
- Traité des membranes (Treatise on Membranes)
- Recherches physiologiques sur la vie et la mort (Physiological Research on Life and Death)
- Anatomie Générale (General Anatomy) Volumes I & II
Who is the father of pathology?
Rudolf Virchow, a physician, pathologist, and politician, made profound contributions to cellular pathology. Hence, he is now known as the “father of pathology.” His works helped us better understand the nature of diseases. And, how they can be accurately diagnosed on a cellular level.
Virchow was born on October 13, 1821, in Schivelbein, Prussia. He studied medicine in Berlin and graduated as a medical doctor in 1843. He published a journal with his friend, Benino Reinhardt, which was later renamed “Virchow’s Archives”. To this day, it continues to publish cutting-edge research articles on human pathology.
Virchow recognized the importance of the microscope for its ability to view the cell’s activities. He made advancements in science and human anatomy using this tool. One of these was discovering the cell theory’s last principle in 1850 when he observed the process of cell division.
Contributions
- All cells come from preexisting cells. Virchow added the final principle of the cell theory. It supports biogenesis, which states that living organisms arise from other living organisms. He emphasized that cells are formed by the division of other cells, either through mitosis or meiosis.
- Cellular pathology. According to Virchow, diseases arose in individual cells rather than tissues or organs. He argued that abnormalities and trauma within the cell caused it to manifest in tissues and organs.
- Embolism connection to metastatic inflammation. Virchow coined the terms “thrombus” and “embolism”. An embolism is the blockage of a blood vessel by an embolus (e.g. blood clot). Metastatic inflammation refers to inflammation caused by the spread of cancer cells.
He speculated that embolism was the most common cause of metastatic inflammation of the lungs. He was able to confirm this by comparing several cases. He also observed that thrombosis was present in these blood vessels where the cancer cells were.
- Medical Education in Germany. Virchow was a teacher at the University of Würzburg and the University of Berlin. His expansive knowledge of medicine, coupled with a passion for teaching, produced many brilliant minds. Some even became famous scientists.
Publications
- Archiv für pathologische Anatomie und Physiologie, und für klinische Medizin (Archives for Pathological Anatomy and Physiology, and for Clinical Medicine) (now Virchow’s Archives)
- Die Cellularpathologie in ihrer Begründung auf physiologische und pathologische Gewebelehre (Cellular Pathology as Based upon Physiological and Pathological Histology)
- Handbuch der speziellen Pathologie und Therapie (Handbook of Special Pathology and Therapeutics)
Who are the scientists who contributed to histology?
Aside from Bichat, other notable scientists who made contributions to the development of histology are Schwann, Schleiden, Cajal, and Ehrlich.
- Schwann
Theodor Schwann was a German physiologist known for his contributions to developing the cell theory. He and Matthias Schleiden proposed that cells are the basic structural unit of life. Specifically, he stated that cells are the fundamental unit of animal structure.
Schwann also identified the role of the myelin sheath covering the axons in the peripheral nervous system (PNS). These were named Schwann cells. They are responsible for insulating axons to facilitate faster transmission of electrical impulses.
- Schlieden
Matthias Jakob Schleiden is a German botanist who proposed that cells are the fundamental unit of plant structure. He and Schwann collaborated to find a unit of organisms similar to both plants and animals.
Schwann also did research on cytogenesis. He recognized the importance of the nucleus in cell formation. He described the cell division process and included the activities of the nucleus. However, a more detailed version of cell division was developed at a later time.
- Cajal
Santiago Ramón y Cajal was a Spanish histologist and neuroscientist. He is credited for establishing the neuron as the fundamental unit of the nervous system. It revolutionized our understanding of the brain and the nervous system.
The properties of nervous tissues and other components of the nervous system are distinct from the rest of the body. Cajal developed the gold stain so you could clearly visualize the neurons and differentiate them from other cells. It is also useful for diagnosing brain tumors.
- Ehrlich
Paul Ehrlich is a German scientist known for developing dyeing and staining techniques. These allowed you to study various cells that could be better viewed with specific dyes (e.g. erythrocytes and leukocytes). It was also significant in the diagnosis of anemia, leukemia, and other blood disorders.
The principle of chemical affinity should be considered when staining. Ehrlich discovered that histological dyes could be acidic, basic, or neutral. They should be paired according to the pH of the tissue or cell.
Who studies histology?
Before knowing who studies histology, you must first know the meaning of histology. Histology is the study of tissues. It involves examining the structure of tissues in relation to their functions. The findings on human tissues enhanced our understanding of diseases.
Professions related to medicine, biology, healthcare, and research study histology. In medicine, histologists and histopathologists use tissue knowledge in the patient’s treatment. They assist other health professionals by analyzing tissue samples under the microscope.
Medical students also benefit from histology. It was made into a prerequisite subject designed to lay a foundation for more advanced medical concepts. A solid understanding of histology will help students grasp the intricate details of human anatomy.
Other healthcare professionals (nurses and physical therapists) study histology to treat tissue- related injuries. They need to be informed about how first-aid procedures and therapy can affect wounds, lacerations, or bruises. For example, discoloration can be a sign of tissue trauma.
Histology can also answer questions on how tissues are affected by drugs and medicine. Pharmacologists and pharmacists must learn histology to ensure that any medicine is safe to consume. They must know the right dosage so as not to cause harm to patients.
Biomedical researchers also study histology to expand the existing literature in this field. New applications can be discovered through past findings by scientists. Human histology can also be compared to plant histology and the histology of other animals.
What is the purpose of histologic examination?
Histologic examinations are when tissue samples are examined under a microscope. It is performed to check for abnormalities in cells or tissues. A histologic examination is carried out by a histopathologist or a pathologist.
These physicians do a histological examination to diagnose diseases. They assess whether a tumor is malignant (cancerous) or benign. They also check for infections, inflammations, and autoimmune diseases. It confirms the suspicions of physicians from the patient’s physical examination.
A histologic examination is also useful for understanding tissue function and structure. Through the years, observation of tissue specimens has led to the accumulation of valuable information. For example, people can now differentiate a healthy tissue from a diseased one.
Types of histological examination
There are two methods for performing histological examination: standard and urgent. They differ based on the purpose and duration. You use standard for routine, non-emergency procedures. It can be for annual follow-up check-ups or benign tumors.
In a standard histological examination, tissue preparation lasts for several hours or days. The process of tissue preparation, which involves fixing up to staining, will take its usual duration.
When the patient is going to have emergency surgery, you request an urgent histological examination. It is when the state of the tissue or cells must be found within the hour. It provides crucial information to guide medical decisions, which can be life or death for the patient.
What is the aim of histology?
The primary aim of histology is to determine how tissues are organized across various structural levels. This allows us to comprehend how different tissues maintain a healthy body or heal or regenerate from a disease.
Histology also aims to study how tissue and cell structure correlate to their function. It is essential to learn how they interact. Further research can be done on this principle. It offers new opportunities for improving diagnostics to address emerging health issues.
It was mentioned previously that histology is useful for diagnosing diseases. More diseases are emerging. Histology remains a crucial tool that is helpful for identifying the causative agents of such diseases.
Conclusion
Histology changed the course of medicine and healthcare. It has become an essential tool in saving and improving the lives of people. It is useful for diagnosing diseases, understanding the structure and function of tissues, and tracking disease progression.
Many scientists, such as Bichat and Virchow, contributed to the field of histology and pathology. Their discoveries and developments led to new theories that were later proven by other scientists. Using their findings, today’s scientists further our understanding of the human body.
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