[On the ultrastructure of the lacrimal gland in pigs (Sus scropha L.) (author's transl)].

The lacrimal gland of pigs has been investigated light- and electron microscopically. Among others the results are as follows: 1. The lacrimal gland of pigs is a tubuloacinar or compound acinar gland. Acini often are elongated. Tubuli and acini are enclosed in a basal lamina with some myoepithelial cells. 2. Tubuli and acini consist of mucoserous, mucous and serous cells. Mucoserous cells predominate and show secretory granules with a typical bipartite structure. 3. Like salivary glands, the lacrimal gland of pigs has a prominent duct system. Intercalated ducts have a stratified cuboidal epithelium. The cells of the proximal part contain secretory granules. The intercalated duct continues into the striated duct. Cells here are tall or columnar in shape and show basal striation, which by electron microscopy is resolved as basal invaginations of the plasma membrane with numerous elongated mitochondria in the pockets of cytoplasm so formed. Excretory ducts commence with pseudostratified columnar epithelium. 4. Terminal nerve fibres penetrate the basal lamina and make contakt with the glandular cells, the myoepithelial cells and the duct cells. The terminal axons contain abundantly synaptic vesicles, sporadic dense cored vesicles and mitochondria. Until now, we could not find any specialized presynaptic or postsynaptic membranes.