Comparison of PTHrP expression in the epididymis of juvenile and adult European bisons.

The aim of the present study was to compare the expression of PTHrP in the epididymes of adult European bisons, and 12- and 5-month-old calves. The highest PTHrP expression was observed in adult animals in muscle cells and endothelium of large vessels, and in muscle cells of the epididymal duct. In one-year-old calves, the reaction was weaker than in adult bulls, being the weakest in 5-month-old calves. However, in small vessels of adult animals, in vascular cells and smooth muscle cells the reaction for PTHrP was considerably weak, being weaker in one-year-old calves, and negative in 5-month-old calves. A similar trace reaction was observed in muscle cells of the epididymal duct in 5- and 12-month-old calves. The present study has revealed that PTHrP expression in vascular and extravascular smooth muscle cells and endothelial cells in European bison is correlated with the animal age and size of the organ.