Abstract: To study histochemical and ultrastructural effects of Se deficiency on mast cells of jejunums in the chicken. 10
chicks were randomly divided into two groups (control group and Se deficiency group). The chicks were killed by decapitation at 75 d and then the jejunums were collected. Microstructure and ultrastructure of jejunums were observed using routine toluidine blue(RTB),long toluidine blue(LTB),alcian blue safranin (AB-S), aldehyde fuchsin alcian blue(AF-AB), alcian blue-periodic acid Schiff reaction(AB-PAS)and transmission electron microscope technology. Results showed that these mast cells had heterogeneity in quantity,shapes,sizes,colouration,mucopolysaccharides with the different staining methods, it may hint that these cells were divided into different subtypes. The amount of mast cells increased obviously in Se deficiency group, it shows that mast cells are one of the substaintial immunocyte and play an important part in immunological regulation. Under transmission electron microscope,abundant homogeneous cytoplasmic granules of different electron density were seen in cytolymph, nucleolus was spherical or oval, complexs of Golgi and major mitochondrias were observed in periplast. In Se difeciency group,it was seen that MC increased significantly and were close together with degenerating cells,heterochromatin increased, nucleus became unsymmetric, periplast was sparse and vacuoles were observed after cytoplasmic granules released the content.

Key words: Se deficiency; mast cell; histochemistry; ultramicrostructure; chicken