GLYCOHISTOGENESIS OF SHEEP ENZOOTIC NASALTUMOUR

This work is aimed to the glycohistochemical characterization of the sheep enzootic nasal tumour (ENT)1 and to correlate it with the glucidic profile of normal nasal mucosa in order to hypothesize the histological origin of the tumour. ENT and contiguous macroscopically normal nasal mucosa from ethmoidal turbinates were collected from 2 adult Lacaune sheep that were euthanized due to chronic wasting disease with nasal discharge, dyspnoea and sneezing. Normal nasal mucosa were also removed from 5 healthy sheep. Collected tissues were treated for both conventional and lectin histochemistry. Normal samples from healthy and ill sheep showed the same reactivity. ENT is composed by papillary and tubular components. The papillary portion produces both secretion and surface glycoconjugates, represented by sulphated glycosaminoglycans and by neutral and sialilated glycoproteins. The tubular portion expresses neutral and sialilated glycoproteins as surface glycoconjugates. Most noticeable data is the expression by the both ENT growth patterns of C4 acetylated sialoderivatives which could confer a resistance towards pathogen agents to the tumour cells, while C4 acetylated sialic acids are lacking in normal nasal mucosa. On the basis of some analogies, such as the prevailing expression of secreting glycoconjugates like highly sulphated glycosaminoglycans and acid glycoproteins, we hypothesize the origin of the ENT papillary portion from the respiratory glands with a possible involvement of the goblet cells. Other analogies, such as the prevailing expression of neutral surface glycoproteins, allow us to suppose the tubular portion belonging from the olfactory glands. Reference 1. De las Heras M et al. Eur J Vet Pathol 1998;4:1-5.