RESUMO
This study describes the histochemical characteristics and ultrastructure of mast cells from tongue, proventriculus, ileum and fabricius bursa, in pheasant (Phasianus colchicus) by light and electron microscopy. We compared the stainability of 4 different methods, toluidine blue, alcian blue, congo red and alkaline Giemsa, to stain mast cell granules from fixed pheasant organs in three different fixatives, 10% neutral buffered formalin, Carnoy's solution or half-strength Karnovsky's solution. Mast cells in all experimental organs were not stained with 4 different staining methods after fixation in 10% neutral buffered formalin but well stained in fixed organs with half-strength Karnovsky's solution. The mast cells had many metachromatic granules stained with toluidine blue or alkaline Giemsa and orthochromatic granules stained with alcian blue or congo red in tissues fixed in half-strength Karnovsky's solution. In electron microscopy, pheasant mast cells were oval, triangular, spindle-like or irregular and had a few finger-like cytoplasmic processes. There were the membrane-bounded secretory granules and the well-developed organelles in mast cells. Internal large granules were oval or irregular, and had variable shape; some higher or lower electron density with homogeneous appearance; some had a particular appearance, and a few showed reticular or spongy-like structure. This indicates that 10% neutral buffered formalin or Carnoy's fixation may be inadequate for detection of mast cells in pheasant, whereas the half-strength Karnovsky's fixation provides metachromatic or orthochromatic staining of mast cell granules.