Chapter VII 



DETAILED DISTRIBUTION OF MAST CELLS IN CATTLE 

 AND IN THE RAT 



MAST CELLS IN CATTLE 



THE classical mast cell-heparin hypothesis was based on the study of 

 mast cells in ox liver capsule (Holmgren and Wilander, 1937). It seemed 

 advisable, therefore, to make a comprehensive survey of the tissue mast 

 cells in cattle. 



All material was collected fresh at the slaughter house and was fixed at once. 

 Tissue blocks were placed in formol-corrosive or in a freshly prepared 4 per cent 

 solution of basic lead acetate clarified by the addition of a few drops of glacial 

 acetic acid. Tissue spreads were fixed in 80 per cent alcohol. No advantage 

 was seen to follow the use of alcoholic stains on this material providing the 

 initial fixation had been adequate: accordingly, 0-1 per cent aqueous toluidine 

 blue was used throughout. On the other hand, it was found that contact 

 with water prior to fixation led to a rapid dissolution of the mast cells (Riley, 

 1954). The significance of this will be discussed later. 



The following tissues were examined. Sections of brain, thyroid, lung, 

 thymus, aorta and superior vena cava, liver, kidney, adrenals, bladder, spleen, 

 large and small intestine, lymph node, skin, muscle and tendon, synovia and 

 pericapsular tissues of the ankle joint. Tissue spreads of dura mater, thyroid 

 capsule, pleura (visceral and parietal), pericardium (visceral and parietal), 

 liver capsule, kidney capsule, peritoneum, subcutaneous connective tissue and 

 tendon sheath. Representative illustrations are shown in Figures 2-10. 



Results. The outstanding finding from this survey of mast cells in cattle 

 is the extraordinarily high mast-cell content of the capsules and serous membranes 

 of the various organs. No conception of the mast-cell content of such mem- 

 branes is obtained from a study limited to paraffin sections cut vertical to the 

 surface of the organ in the conventional manner. Nor are the mast cells 

 invariably, or even usually, related to the blood vessels in these capsules. 

 This is particularly evident when tissue spreads of ox liver capsule and ox 

 visceral pleura are examined (Figs. 6 and 9). 



Further confirmation of this lack of relationship of mast cells to blood 

 vessels in serous membranes was obtained by injecting the vessels. Lobes of 

 lung and liver from freshly killed animals were washed out with warm Tyrode's 

 fluid and injected (either by vein or artery) with a 10 per cent (v/v) solution of 

 India ink in saline before stripping the 'capsule' and preparing the tissue 



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