MAST CELL IN EVOLUTION 



Higher vertebrates, including man. Ehrlich (1877) and his pupil 

 Westphal (1891) found tissue mast cells to be numerous in cat, dog, goat, rat, 

 bat, and calf; rare in rabbit, hare, and guinea pig. Later, Zimmermann (1908), 

 using the excellent histological technique devised by his colleague Schaffer 

 (1907), showed that tissue mast cells are rather more common in the guinea 

 pig than Ehrlich believed and that they occur at the usual sites for mast cells 

 in mammals, namely in loose connective tissue generally and especially around 

 blood vessels, between fat cells, in peritoneum, in most organ capsules and in 

 the thymus. The guinea pig also resembles other mammals in that mast cells 

 are absent from the central nervous system. According to Krabbe (1928) the 

 hedgehog alone among the mammals has mast cells within the substance of 

 the brain, the cells being particularly common in the habenular ganglion. 

 There is general agreement with the findings of Ehrlich and Westphal regarding 

 mast cells in the other species which they examined. Much of our knowledge 

 of tissue mast cells in the embryonic and adult forms of higher vertebrates is 

 due to the painstaking studies of Maximow (1906; 1910; 1913; 1924) who 

 strengthened and expanded the views of Ehrlich and Westphal and dealt 

 summarily with their critics. 



In his thesis Westphal (1891) mentions the variations in size of the granules 

 in mast cells of different species. Comparatively coarse in rat, mouse and 

 guinea pig the granules are small in birds and dust-like in amphibia. The name 

 'mast cell' as defined by Ehrlich (1878; 1879) is thus now more appropriate 

 for the cells with basophilic metachromatic granules in the higher vertebrates 

 than is the term 'coarse granulocyte' which we found convenient for describing 

 the homologues of mast cells with variable staining properties in the tissues of 

 lower organisms. 



Minor differences in distribution of mast cells are found in mammals as 

 in lower vertebrates, the liver again providing a good example of the variation 

 in the mast-cell pattern among related species. Thus the cells are exceptionally 

 large and numerous in the capsule of ox liver (Holmgren and Wilander, 1937), 

 whereas in the liver of the dog they are small and are found near the portal 

 tracts and scattered diffusely throughout the liver parenchyma (Nagayo, 1928). 

 In contrast to the high mast-cell content of the liver in ox and dog the liver in 

 rabbit and rat is almost devoid of mast cells (Westphal, 1891 ). Holmgren and 

 Wilander (1937) describe in detail the presence and distribution of mast cells 

 in liver, spleen and lung of cow, calf, sheep, horse, pig, dog and rabbit. Corre- 

 sponding data for mast cells in the gut of several species of mammals are to be 

 found in the paper by Mota, Ferri and Yoneda (1956) and in the early investiga- 

 tions of Hardy and Wesbrook (1895) who emphasize the enormous numbers of 

 'splanchnic basophils' in the submucosa of carnivora. Arvy and Quivy 

 (\955a, b) describe in detail the distribution of mast cells in the alimentary tract 



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