Harderian gland of adult and aged male guinea pig a histological and ultrastructural study

ABSTRACT

The Harderian gland [HG] was studied in mature [4 months] and aged [2 years] male guinea pigs with light and electron microscopic techniques. The glandular tissue showed yellow green autofluorescence. The gland is surrounded by a collagenous capsule. It consisted of compound tubuloalveoli lined by a single layer of epithelial cells and possessing myoepithelial cells within their basal lamina. Semithin sections revealed two types of secretory cells; light and dark. Ultrastructurally three types of secretory cells could be recognized type IA, type IB and type II. Type IA cells were the most readily observable one. The contained numerous lipid vacuoles, but no secretory vesicles. Type IB cells characteristically possessed numerous secretory vesicles with dense core. Type II cells exhibited light cytoplasm containing an elaborate SER, few lipid vacuoles and dilated RER cisternae. The gland is characterized by a specialized duct system within its substance. The gland structure showed several aging changes. These included invasion of the parenchyma with inflammatory cells, frequent detection of both plasma cells and mast cells, degeneration in both the secretory and the myoepithlial cells, increased deposition of connective tissue fibers as well as appearance of numerous immature blood capillaries. The results indicate that the guinea pig HG possesses several peculiar morphological features that deserve further investigations