A fine structural study of the turkey harderian gland.

The ultrastructure of the turkey Harderian gland is described and the findings support previous histological descriptions of the gland. The gland is a compound tubulo-acinar structure composed of characteristic bipolar epithelial cells providing a predominantly merocrine secretion to the lumina. In the basal aspect of the cell, aggregations of non-secretory lipid-like droplets were evident and apically, the secretion was mucoid. The cells had abundant mitochondria, granular endoplasmic reticulum, ribosomes and a complex network of Golgi elements. In the subepithelial regions, myoepithelial cells and large numbers of plasma cells were seen. Within the granular endoplasmic reticulum cisternae of the epithelial cells, fibrillary or crystalline rods in some instances measuring up to 10 micron in length, with a 7.0 nm repeat pattern, were frequently seen.