Mucin profiles of the abomasum in bulls and rams: A comparative study

Many pathogens require direct binding to mucosal cells to cause an infection. The mucosal epithelium of the digestive tract, which is covered by a mucin layer, fulfills several protective functions that are essential to maintaining the health of the digestive tract. Mucins are glycoproteins, which are found on membranes and in mucus gels and protect the underlying mucosal cells. Both membrane-associated mucins and secreted mucins are critical components of mucosal defense. The aim of this study was to determine the localization and expression of mucin profile of the abomasum via histochemistry and immunohistochemistry. The abomasums of 20 bulls and 20 rams were evaluated. Histochemical examination showed that neutral and acidic mucins were present in the mucosa and the glands of the pars cardiaca, fundus, and pars pylorica of the abomasums of both bulls and rams. However, the expression of acidic mucins was weak in the superficial glands and strong in the deep glands of the abomasum of rams. In both bulls and rams, MUC1, MUC5AC, and MUC6 were expressed in the glandular epithelial cells in all regions of the abomasum. Interestingly, while MUC2 was not expressed in the pars cardiaca and fundus, it was weakly expressed in the parietal cells of the pars pylorica in both species. In conclusion, the presence of neutral and acidic mucins and MUC1, MUC2, MUC5AC, and MUC6 proteins in luminal epithelial and glandular cells of abomasum in the bulls and rams support the hypothesis that mucins play a key role in the protection of the abomasal mucosa against infectious agents.