Specifically, human submandibular gland (located beneath the floor of the mouth). A salivary gland is a large compound acinar gland, which means that the secretory cells in the gland are arranged in globular units. These acini secrete their contents into ducts, which get progressively larger as they carry contents from the acini through the secretory portion of the gland, eventually combining in between the lobules of the gland and secreting through one big duct into the mouth. In the picture below, I have labeled an intercalated duct and large interlobular duct. Remember that the lumen of the interlobular duct is a good place to observe stratified columnar epithelium.
The submandibular gland is considered to be a "mixed" secretory gland, that is, it contains serous and mucous acini. I have labeled a purple-staining serous acinus in the picture. There aren't any mucous secreting cells in this frame, but they are in the tissue somewhere. This gland produces saliva (from the mucous acini) and salivary enzymes like amylase (from the serous acini).
Salivary glands are also good places to observe blood vessels, adipose tissue, and light pink connective tissue. In this picture, you can also see infiltrating lymphocytes (the little purple cells) indicating that some sort of immune response was occurring.
