Abstract
The fine structure of the lacrimal gland and its changes of the secretory cycle have been studied by light and electron microscopy, on the rat.
1. The acinar cell contains only one kind of the secretory granule which is surrounded by a thin membrane originated from the Golgi membranes, and its contents are low in density, water-rich and not mucous. The secretory granule is extruded in a typical mode of merocrine secretion into the lumen.
2. Both in the small and larger ducts, dense secretory granules are found in their epithelial cells and seem to be formed within the Golgi complex. The mechanism of granule release is not clear but the apocrine-like processes are often found. No typical infolding of the basal plasma membrane is observable and intercellular boundaries are characterized by well-developed cellular interdigitation in complex arrangement.
3. The myoepithelial cells are present in the terminal portion and duct system which is lined with the epithelial cells containing secretory granules.
4. Unmyelinated nerve fibers are sometimes found in the interstitial connective tissue among acini, but there is no evidence of direct attachment of nerve fibers to the acinar cells or myoepithelial cells.
