title: Morphological observations on the harderian gland of the North American opossum (Didelphis virginiana).
abstract: The Harderian gland of the North American opossum (Didelphis virginiana) is large and well developed, despite the absence of a nictitating membrane in the adult of this species. The elongate glands are surrounded by a delicate connective tissue capsule from which thin septae extend, subdividing the gland into numerous lobules. The secretory units of the opossum Harderian gland are drained by a well defined but not extensive intralobular and interlobular duct system. Most of the secretory end pieces consist of tubulo-alveolar units with widely dilated lumina filled with secretory product. Numerous intact lipid vesicles suspended within an amorphous material constitute the luminal contents. Cells lining the tubulo-alveolar secretory end-pieces are usually columnar in shape, and characterized by numerous lipid-containing secretory vesicles and aggregations of poly-tubular complexes 40-60 nm in diameter. In addition, these cells contain numerous large irregularly shaped mitochondria, whose matrix is of considerable electron density. Intralobular and interlobular ducts are lined by electron-lucent epithelial cells that lack both the lipid-containing vesicles and the large mitochondria, although typical smaller mitochondria are found scattered within the cytoplasm. Both secretory end-pieces and ductal elements are invested by an abundance of myoepithelial cells. A second, smaller serous type of secretory unit may occur near the centre of some Harderian gland lobules. In these units secretory tubules and acini are compactly arranged surrounding a narrow lumen. Serous cells are pyramidal in shape and the cytoplasm is characterized by numerous electron-dense secretory granules and scattered profiles of rough endoplasmic reticulum.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Anatomy, University of Missouri, Columbia.
authors.forename: W J
authors.initials: WJ
authors.lastname: Krause
authors.forename: P G
authors.initials: PG
authors.lastname: McMenamin
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D004847:Epithelial Cells; D004848:Epithelium / Q000648:ultrastructure; D005260:Female; D006243:Harderian Gland / Q000033:anatomy & histology* / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D009893:Opossums / Q000033:anatomy & histology*