Histology Health Dictionary

The structure of the body of any living thing, and its scientific study. Human anatomy, together with physiology (the study of the functioning of the body), forms the foundation of medical science. Anatomy is subdivided into many branches. These include comparative anatomy (the study of the differences between human and animal bodies), surgical anatomy (the practical knowledge required by surgeons), embryology (the study of structural changes that occur during the development of the embryo and fetus), systematic anatomy (the study of the structure of particular body systems), and cytology and histology (the microscopic study of cells and tissues respectively).... anatomy

The study of how disease changes the anatomy (histopathology-and histology) of tissues.... pathology

An acute arbovirus (see ARBOVIRUSES) infection caused by a ?avivirus of the togavirus family, transmitted from animals to humans by various species of forest mosquito (jungle/sylvan yellow fever), and from human to human by Aëdes aegypti (urban yellow fever). Mosquito transmission was shown by Walter Reed and his colleagues in 1900. It is ENDEMIC in much of tropical Africa and Central and South America but does not occur in Asia. In the urban cycle, humans constitute the reservoir of infection, and in the jungle/sylvan variety, mammals – especially subhuman primates – are involved in transmission. Historically, yellow fever was enormously important, causing devastating epidemics (see EPIDEMIC); it also carried a high mortality rate in travellers and explorers. Differentiation from other infections associated with JAUNDICE was often impossible.

Clinically, yellow fever is characterised by jaundice, fever, chills, headache, gastrointestinal haemorrhage(s), and ALBUMINURIA. The incubation period is 3–6 (up to 10) days. Differentiation from viral hepatitides, other viral haemorrhagic fevers, severe Plasmodium falciparum malaria, and several other infections is often impossible without sophisticated investigative techniques. Infection carries a high mortality rate. Liver histology (biopsy is contraindicated due to the haemorrhagic diathesis) shows characteristic changes; a fulminating hepatic infection is often present. Acute in?ammation of the kidneys and an in?amed, congested gastric mucosa, often accompanied by haemorrhage, are also demonstrable; myocardial involvement often occurs. Diagnosis is primarily based on virological techniques; serological tests are also of value. Yellow fever should be suspected in any travellers from an endemic area.

Management consists of instituting techniques for acute hepatocellular (liver-cell) failure. The affected individual should be kept in an isolation unit, away from mosquitoes which could transmit the disease to a healthy individual. Formerly, laboratory infections were occasionally acquired from infected blood samples. Prophylactically, a satisfactory attenuated VACCINE (17D) has been available for around 60 years; this is given subcutaneously and provides an individual with excellent protection for ten years; international certi?cates are valid for this length of time. Every traveller to an endemic area should be immunised; this is mandatory for entry to countries where the infection is endemic.... yellow fever

A diagnostic test in which a small amount of tissue or cells are removed from the body for microscopic examination. It is an accurate method of diagnosing many illnesses, including cancer. Microscopic examination of tissue (histology) or of cells (cytology) usually gives a correct diagnosis.

There are several types of biopsy. In excisional biopsy, the whole abnormal area is removed for study. Incisional biopsy involves cutting away a small sample of skin or muscle for analysis. In a needle biopsy, a needle is inserted through the skin and into the organ or tumour to be investigated. Aspiration biopsy uses a needle and syringe to remove cells from a solid lump. Guided biopsy uses ultrasound scanning or CT scanning to locate the area of tissue to be biopsied and to follow the progress of the needle. In endoscopic biopsy, an endoscope is passed into the organ to be investigated and an attachment is used to take a sample from the lining of accessible hollow organs and structures, such as the lungs, stomach, colon, and bladder. In an open biopsy, a surgeon opens a body cavity to reveal a diseased organ or tumour and removes a sample of tissue. Prompt analysis, in some cases by frozen section, can enable the surgeon to decide whether to remove the entire diseased area immediately.... biopsy

A branch of histology concerned with the effects of disease on the microscopic structure of tissues.... histopathology

(acidophilic) adj. 1. (in histology) describing tissues, cells, or parts of cells that stain with acid dyes (such as eosin). See also adenoma. 2. (in bacteriology) describing bacteria that grow well in acid media.... acidophil

treatment given to patients after the primary therapy, which is usually surgical removal of the tumour, when there is a high risk of future recurrence based on tumour stage and histology. Adjuvant therapy is aimed at destroying these microscopic tumour cells either locally (e.g. adjuvant breast irradiation after breast-conserving surgery) or systemically (e.g. adjuvant chemotherapy may be recommended for patients with breast cancer, colorectal cancer, and other types of cancer). Compare neoadjuvant chemotherapy.... adjuvant therapy

n. 1. (in histology) the substance of a tissue or organ in which more specialized structures are embedded; for example, the ground substance (extracellular matrix) of connective tissue. 2. (in radiology) the division of an image into rows and columns with equally sized elements (*pixels). The final image is completed by assigning a density to each of these elements. Increasing the number of pixels in the matrix improves the resolution of the final image. A typical value could be 256 rows × 256 columns.... matrix

n. excision of a single mammary duct that is causing nipple discharge. The duct is sent for histology to determine the presence of a papilloma or carcinoma.... microdochectomy

a surgical technique used for removing primarily high-risk nonmelanoma skin cancers, particularly basal cell carcinoma. The technique allows the surgeon to see beyond the visible tumour as the specimen is removed and the histology checked in stages. At each stage, if the tumour involves the margins, further tissue is resected until they are clear. There is an extremely high cure rate. [F. E. Mohs (1910–2002), US surgeon]... mohs’ micrographic surgery