Spectrin Localization in Bursa of Fabricius and Thymus in Chickens.

Abstract

Spectrin localizations were immunohistochemically observed by light and electron microscopies in bursa of Fabricius and thymus in chickens. Many bursal lymphocytes were detected as spectrin-positive. These spectrin-positivecells (SPC) were located in the follicular medulla in bursa and the cortical lymphocytes were detected as spectrinnegative. Interestingly, SPC was negligible in thymus. When tissue sections were pretreated with heating at 90°C for antigenicity retrieval of cytoskeletal proteins in aldehyde-fixed-sections before incubation with anti-spectrin, an enhancement on the stain intensity was noted and the degree of enhancement was dramatic. Strong stainings of spectrin were present in the epithelium of the mucosal fold, but was not apparent in follicle-associated epithelium. Furthermore, heat-induced antigenicity retrieval was not assessed in the interfollicular surface epithelium. Although the stain intensity was still weak, thymic lymphocytes were observed as spectrin-positive after heating at 90°C. Among the thymic SPC, epithelial cells were more strongly stained than the lymphocytes after the same pretreatment. Therefore, heating had an enhancing effect on stain intensity of spectrin that is partially susceptible to aldehyde fixation. Ultrastructurally, spectrin was mainly detected as aggregated or diffusive type in the cytoplasm after heating at 90°C. Any difference of subcellular localizations of Spectrin was not seen between the bursal and thymic SPC.