The mast cell nature of granule cells in the digestive tract of the pike, Esox lucius: Similarity to mammalian mucosal mast cells and globule leucocytes

Observations were made on sections of intestinal tissue from the pike, Esox lucius, fixed in a solution containing 4% formaldehyde and 5% acetic acid in methanol. Four staining procedures, using May-Grunwald Giemsa combination dye, hematoxylin and eosin, toluidine blue, and alcian blue in sequence with safranin, were applied. Numerous granule cells were found in the area of stratum compactum and in the lamina propria. Granule cells were also present in connective tissue extending from the lamina propria into the mucosal folds, between the circular and the longitudinal smooth muscle layer of the intestine and in attached mesenteric tissue, and some were encountered within the intestinal epithelium. Independent of tissue location of the granule cells, their granules stained violet blue with May-Grunwald Giemsa stain, red with hematoxylin and eosin, blue after alcian blue followed by safranin, and showed purple metachromasia when stained with toluidine blue. The present histological observations indicate that the granule cells in the intestine of the pike are mast cells, with staining characteristics resembling those of mammalian mucosal mast cells and globule leucocytes. (C) 1996 Academic Press Limited.