Summary

Specimens from the Harderian gland, the lacrimal gland and bursa of Fabricius in ducks with chlamy-diosis were processed by the classical histological methods and permanent preparations were ob-tained. On single and serial histological cross-sections from material fixed in non-aqueous fixator, histochemical tests for PAS reactivity, staining with alcian blue at pH 1.0 and 2.5 as well as staining with Mowrys alcian blue followed by PAS reaction were performed. The light microscopic observa-tion did not reveal considerable changes in the lacrimal gland. Structural and functional changes with various character and degree in the central lobular parts of the Harderian gland, the epithelium, the propria and thymus-like lobules of the bursa of Fabricius were observed. The histochemical analyses showed that the secretion of intraorbital glands in Mulard ducks was with a heteropolysaccharide nature, similarly to that in other waterfowl