Immunohistochemical localization of transferrin in the pre- and postnatal bovine brain

The distribution of transferrin in brains from fetuses (age-range: 1-2 to 8-9 months of gestational age), calves, subadult (between 1 day and 9 months old) and adult cattle (> 12 months old) were examined by immunohistochemistry. In both pre- and postnatal brains transferrin was predominantly found in oligodendrocytes. Furthermore, transferrin immunostaining was present in single to few neurons, within the lumina of vessels, in endothelial cells, in epithelial cells of the choroid plexus and in ependymal cells. A caudo-rostral progress in the appearance of transferrin-positive cells was found. In fetuses, transferrin-positive mature oligodendrocytes and neurons were not detected before 3-4 months of gestational age. Findings in different brain areas of older fetuses suggest an association between the increase of transferrin-positive oligodendrocytes and the process of myelination. In brains from calves and sub-adult cattle a continuous decrease of transferrin-immunoreactive oligodendrocytes and neurons was noted.