This is of added interest because the medial segment in ducks is homologous with both the lateral nasal gland of reptiles and Stenson's gland in mammals whereas the lateral segment is a similar, but separate, septal nasal gland. These medial and lateral segments are compound tubular glands formed of two cell types. The first of these are cuboidal, peripheral cells located near the end of each secretory tubule. They are relatively small cells, often triangular in shape, lacking basal infoldings and having only a small number of mitochondria. The second type are principal cells which are found along the entire length of the secretory tubule