Lives of the fellows

Anthony Guy Everson Pearse

b.9 August 1916 d.24 May 2003
MRCS LRCP(1940) MB BChir Cantab(1941) MA(1942) DCP London(1947) MD(1950) MRCP(1957) Hon MD Basel(1960) FRCPath(1963) FRCP(1964)

Tony Pearse had a worldwide influence on the use of histochemistry as a modern research and diagnostic tool, and inspired new understanding of the relationship between neural and endocrine systems.

Pearse's medical education was at Trinity College, Cambridge, and St Bartholomew's Hospital. During the Second World War he served in the Royal Navy as a surgeon lieutenant: his battleship experience made a deep impression on him. After the war he became assistant lecturer in the morbid anatomy (later histopathology) department at the Postgraduate Medical School of London at Hammersmith Hospital, where he spent the rest of his career, becoming consultant pathologist in 1951.

Tony Pearse had an inquiring and scientific attitude to pathology and a profound knowledge of chemistry. He was not satisfied with the current histological staining methods, some of them not even understood chemically but known to 'work', used to distinguish one type of tissue from another, believing that the understanding of pathological processes depended on knowledge of the underlying cellular chemistry. Alongside his diagnostic responsibilities, he set out to test and develop histochemical methods for the accurate microscopical localisation of cell constituents, in particular of endogenous enzymes. Although histochemistry had been in development for over 100 years, it was Pearse who put it on the map for biomedical science and diagnostic pathology.

For sectioning the necessary frozen samples, Pearse developed a new model of crysostat, an externally operated microtome housed in a refrigerated cabinet. The very successful prototype was taken up commercially, and modern cryostats still follow the same principles. Some years later, his design skills resulted in a convenient, bench-top tissue freeze-drier, also adopted by a manufacturer.

He was able to show the characteristic constituents of different cell types and even of their sub-cellular organelles such as mitochondria and lysosomes that were then being revealed by the emerging technique of electron microscopy. Many of the enzyme localisation methods that he recommended became standard diagnostic tests, for example, in muscle disease. These important finings were gathered together into his magnum opus Histochemistry: theoretical and applied, etc (London, J & A Churchill, 1953). This book established Pearse's reputation as a world expert in histochemistry. It was translated into Russian, Polish and Spanish, and inspired scientists all over the world. The complex chemical reactions were explained clearly, often with diagrams, results were illustrated with photomicrographs and every reaction for which a method was given had been authenticated by Pearse himself and his few assistants in his very limited laboratory space. The subject expanded so much that enlarged editions came out in 1960 and 1968. The fourth (final) version, co-edited and multi-authored, was in three volumes, published in 1980, 1985 and 1991.

Thanks to the book and his papers, he was frequently invited to lecture abroad and always returned carrying potentially useful chemicals in vials labelled with obscure formulae. Aspiring histochemists flocked to his laboratory, where he was teacher, guide and friend to more than 200 from over 40 countries. The atmosphere in the cramped laboratory was enthusiastic, dedicated and, by necessity, communal and fostered many discussions and lasting friendships. It must he said that Pearse made little attempt to adapt his habitual mumble for bemused non-English speakers, but his attitude to their research ideas was always generous, stimulating and helpful; he was never too busy to see his colleagues and welcomed their input which he invariably acknowledged with gratitude. His research fellows were good scientists in their own right, having been selected by competition for the privilege of a visit, and often became leaders in their fields. Their memoirs for his retirement in 1981 reflect the great respect and affection in which they held him.

In 1965 he was created the first professor of histochemistry and given his own autonomous department. About this time, Pearse collaborated with the endocrinologists at Hammersmith in localising the newly discovered hormone, calcitonin, to the interfollicular C cells of the thyroid gland. This drew his attention to the histochemical similarities between cells of the nervous system and those of the 'diffuse endocrine system', many scattered along the gastrointestinal tract, presumably secreting as yet undiscovered peptide hormones. Their properties included amine precursor uptake and decarboxylation (APUD) which resulted in characteristic fluorescence after reaction with formaldehyde.

In birds and lower vertebrates, however, calcitonin was localised to the ultimobranchial gland, a neural crest derivative. This sparked Pearse's theory that similarities between the nervous and diffuse endocrine systems were due to their common embryological origin in the neural crest. Fortuitously, he and his colleagues were able to prove that this was, indeed, the origin of the C cells.

The APUD theory then took off. The various APUD cells of the gut were characterised as producing many newly identified regulatory peptides. The common origin theory was boosted by the discovery of identical peptides in nerves and the diffuse endocrine system was re-named the 'diffuse neuroendocrine system'. However, several groups of experimental embryologists investigating the neural crest or neural ectoderm derivation of the gastrointestinal APUD cells succeeded only in disproving this part of the hypothesis, which was eventually abandoned. Nevertheless, Pearse had initiated a new and now established way of thinking about the conjunction of nerves and regulatory peptide-secreting cells in a unified neuroendocrine controlling system.

Pearse's interest included comparative endocrinology, and his laboratory was often populated by quails, turtles, frogs, fishes, lampreys, amphioxus, snails or worms, in all of which he and others found regulatory peptides resembling mammalian ones and, in chordates, produced in typical APUD cells.

Many learned societies and overseas universities honoured his achievements, but he was unassuming and disliked the internal politics needed for personal advancement. His many foreign students looked on him as the epitome of a courteous English gentleman.

He was devoted to science, and also to his family. He met his wife, Elizabeth Himmelhoch, also a doctor, at Hammersmith, and they married in 1947. They had one son and three daughters. His relaxations were gardening and sailing; these seemed to be hazardous activities, often resulting in his arrival at work on a Monday covered with plasters or with his back put out. He also enjoyed his international travel and made numerous close friends among his scientific colleagues.

Susan Van Noorden
Julia M Polak

[The Independent 31 May 2003; The Times 4 Aug 2003]

(Volume XI, page 442)

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