TONY PEARSE was the first ever professor of histochemistry, the exacting science of the microscopical demonstration of biochemical reactions within cells and tissues. This meant using knowledge from the disciplines of biochemistry, physiology and pathology, work in which he was an international leader. He was ahead of his time, though, and it was not until 1965 that he was given his own department and chair. His scholarship was eventually recognised worldwide.
Anthony Pearse was educated at Sherborne, Trinity College, Cambridge, and St Bartholomew’s Hospital Medical School. After the war he joined the histopathology department at the Postgraduate Medical School of London at Hammersmith Hospital, where he spent his working life. He was also a consultant pathologist at Hammersmith Hospital from 1951 until his retirement in 1981.
In the 1950s his interest in biological chemistry prompted him to examine the reactions of cellular organelles, such as mitochondria and lysosomes, rightly believing that they would provide information about normal and diseased tissue to add to that given by conventional histopathological staining methods. Many of the techniques that he advocated are now in diagnostic use, for example, to demonstrate abnormal muscle fibres in muscular dystrophy.
Pearse’s major publication, Histochemistry, Theoretical and Applied was published in 1953 — a hefty book in which he explained the chemical nature of cells and tissues and discussed methods of demonstrating their reactions to conventional and novel microscopical stains. Important to the success of this standard work were the easy-to-use recipes, all of which had been tested in his laboratory.
Pearse’s particular strength was the accurate microscopical demonstration of enzyme activity in tissue sections. Apparatus for cutting sections from the necessary frozen samples was cumbersome and unreliable, so Pearse built a “cryostat”, a refrigerated chamber containing a microtome. Putting all the controls on the outside made it possible to keep the temperature at -20°C — and avoided the dangers of frostbite. The prototype, called “Wheezy”, served faithfully for many years, and was produced commercially. Pearse later designed a freeze-dryer for vacuum drying frozen tissue, and that too was produced commercially.
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In 1966 Pearse noticed that there are many similarities between cells of the nervous system and cells producing peptide hormones, such as insulin and the newly discovered calcitonin. He suggested that this was due to a common embryonic origin, and although this was proved for only a few of the hormone-producing cells, his hypothesis inspired an enormous amount of work in experimental embryology, neurology and endocrinology. It resulted in acknowledgment of a body-wide, diffuse neuroendocrine system producing hormone-like regulatory peptides. The identification methods were valuable in diagnosis, but also in evolutionary studies, which showed that similar systems are present in all animal phyla.
As enzyme histochemistry began to be superseded by immunocytochemistry, Pearse and his colleagues identified many previously unknown peptide hormone-producing cells. This led to the discovery of multiple peptide production by single cells and to the concept of cell plasticity.
Over the years, Pearse received in his cramped laboratory more than 200 scientists from more than 40 countries. He was a stimulating, generous teacher, always open to suggestions and ever-ready to provide hypotheses and explanations.When benefitting from the experiments of his research team members, he was scrupulous in acknowledging their contributions. He was a very modest and straightforward man who avoided institutional political scheming.
In addition to his overwhelming passion for science, he was an enthusiastic gardener. He was also a sailor, his wartime experiences in the Navy having impressed him deeply. He is survived by his wife and four children.
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Professor Anthony Pearse, histochemist, was born on August 9, 1916. He died on May 24, 2003, aged 86.