|A brief History of histology|
The history of histopathology cannot be considered in isolation for it was through the knowledge of anatomy and the development of surgical instruments and procedures that specimens could be obtained for histopathological examination. The work of those who invented stains, discovered anatomy at the microscopic level and diagnosed could not have proceeded without the work of those who came before them in history.
The earliest example of a surgical procedure is found in the skulls of Neolithic man where there is evidence of trepanning.
The ancient Egyptians had an understanding of anatomy. In the tomb of Tutankhamun, 13th century BC, four miniature coffins containing organs such as the liver, spleen, stomach, lungs and intestines, removed before embalming, were found in an alabaster chest. Papyruses show that there were people who were responsible for recognising and treating various diseases. When soldiers were away at war the Egyptian State paid for their treatment.
In Indian, although there was little knowledge of anatomy, there was surgery to remove tonsils and limbs; plastic surgery was also performed on nose.
In China the concepts of Yang - associated with the sun, light, the south, masculinity and dryness, and Yin - associated with the moon, darkness, the north, femininity and moisture, were attributed to Shen Nung under the influence of the Taosit god P'an Ku.
In the 5th century BC Hippocrates on the Greek island of Cos the concept of the four humours was developed, with health being dependent upon a balance of the elements of blood, phlegm, black bile and yellow bile; these representing fire, mucus, earth and air. An excess of any one of these elements would induce a different temperament; melancholia, black bile; choleric, yellow bile; phlegmatic, mucus; and sanguine, blood. The earliest concept of fixation was from Hippocrates who knew about the biological effects of mercury and its salts. The tanning industry lead to the development of new fixatives and in the period of in the 19th century AD many of the fixatives used today were introduced.
Galen was born in Rome in AD130; he recognised that muscles were controlled by the brain. His writing summarized five centuries of medical work and was unrivalled until the 14th century.
After the fall of Rome in the 5th century AD the Arabs studied and translated Greek manuscripts. Rhazes (865- 925) was able to distinguish small pox from measles. Avicenna (980-1037) compiled a canon of medicine that became compulsory reading for European medical students up to the 17th century.
Europe in the 10th century had a medical school in Salerno in Italy, where the students learnt in verse form both surgery and urine examination. New universities developed in Bologna, Paris, Padua, Montpellier and Oxford.
By the Renaissance, Paracelsus (1527) had burnt the books of Galen and Avicenna. Leonardo da Vinci, (1452-1519), undertook dissections and produced anatomical drawings. Pare in France, who died in 1590, introduced surgical instruments and the artificial hand.
Galileo invented the thermometer and Jansen invented the microscope, the value of which was demonstrated by Malpighi (1628 - 1694).
The first half of the 19th century that was dominated by Virchow who established Virchow's Archives in the 1840's. During this century there were developments in microscopy By the 1880s progress had been made in fixation, embedding, sectioning and staining.
Sir John Hill used an extract of logwood to study the microscopic structure of wood, and Joseph von Gerlach used carmine to examine brain specimens. Haematoxylin is extracted from the heartwood of the tree Haematoxylon capechianum, that originates in Mexico but is grown in the West Indies. The haematoxylin is extracted with hot water and precipitated out with urea. It is the oxidative product, haematin, that is the dye.
The earliest concept of fixation was from Hippocrates (400BC) who knew about the biological effects of mercury and its salts. The tanning industry lead to the development of new fixatives and in the period or Virchow many of the fixatives used today were introduced.
In 1856 William Perkin discovered the dye mauve that was used in the early 1860s by F W B Benke of Marlbery. Joseph Janavier Woodward, a surgeon in the US Army, used fuchsine and aniline blue to stain human intestines. Paul Ehrlich realised that the chemical dyes obtained from coal tar did not simply colour cells but combined with the chemical elements within them to form new substances. The Swiss chemist Friedrich Miescher, in 1869 used aniline dyes to examine the cell nucleus. In 1875 Carl Weigart, Ehrlich's cousin, demonstrated the fuchsine derivative methyl violet stained bacteria as opposed to tissue.
Perphaps the greatest leaps forward were in the 20th century that saw the development of electron microscopy, an understanding of enzyme dynamics leading to enzyme histochemistry, the understanding of immunology and the development of poly and monoclonal antibodies and immunocytochemistry. Developments in genetics have lead to an understanding of inherited diseases but also enabled amplification of genetic material using the polymerase chain reaction and gentic probes.
Histopathology is, therefore, a dynamic discipline that has slowly evolved over time using developments in anatomy, surgery, anaesthesia, chemistry, immunology and genetics to develop into the medical laboratory discipline we know today. As histopathology continues along its evolutionary path then the 21st century should see many more developments of technique and greater understanding of disease.