KEY BC, basal cells C, cleft CTP, connective tissue papillae D, ducts Ep, epithelium lining the clefts LCT, loose connective tissue LSG, lingual serous glands NF, nerve fibers NSC, neuroepithelial sensory cells SC, supporting cells SE, stratified nonkeratinized epithelium TP, taste pore
Like the parotid glands, the submandibular glands are located outside of the oral cav-ity. They are located under either side of the floor of the mouth near the mandible. A duct runs forward and medially from each of the two glands to a papilla located on the floor of the mouth just lateral to the frenulum of the tongue. The secretory component of the submandibular glands are the acini which are of three types, namely serous acini that are protein secreting like those of the parotid gland, mucous acini that secrete mucin, and third, acini containing both serous and mucous secreting cells. In the case of the mixed acini, the mucous cells are capped by serous cells, which are typically described as demilumes. Recent studies suggest that the demilume is an artifact of tissue preparation and that all of the cells are aligned to secrete into the acinus lumen. Traditional fixation in formaldehyde appears to expand the mucous cells with the consequent squeezing of the serous cells to form their cap like position. ORIENTATION MICROGRAPH: This micrograph reveals a portion of the sub-mandibular gland. A single well-defined lobe (L) is seen in the upper part of the micro-graph. Within the central portion of the gland, there is a dense connective tissue core (DCT) containing the larger arteries (A), veins (V), and excretory ducts (ED) of the gland. The submandibular gland is a mixed gland; those regions containing serous acini (SA) are darkly stained whereas, regions containing mucous acini (MA) are lighter in appearance. SASASASAMAMASASADCTDCTVVEDEDEDEDAASASAMAMALLSASAMASADCTVEDEDASAMAL
Submandibular gland, human, H&E, ×175.
This micrograph reveals the various components of the sub-mandibular gland. The serous acini (SA) are darkly stained in contrast to the lighter staining mucous acini (MA). Furthermore, the serous acini are generally spherical in shape. The mucous acini are more tubular or elongate and sometimes can be seen to branch. The secretion from the acini enters an intercalated duct. They are the smallest ducts and are of relatively short length. They reside within the lobule, but are often difficult to find because of their shortness.
Submandibular gland, human, H&E, ×725.
The boxed area in the above micrograph is shown here at higher magnification. It includes several mucous acini (MA) on the left side of the micrograph, a number of serous acini (SA) on the right side of the micrograph, and in the center, two mixed acini (MxA) consisting of mucous-secreting cells and serous-secreting cells. Characteristically, the mucous-secreting cells have a pale-staining cytoplasm with their nuclei flattened at the base of the cell. In contrast, the serous-secreting cells are deeply stained and exhibit round nuclei. In addition, the lumen (Lu) of the acini associated with the mucous se-These ducts, in turn, empty into the larger striated duct (SD). This type of duct is better demonstrated in the micrograph below. Their contents then empty into an excretory duct (ED) which is recognized by a stratified or pseudostratified epithelium. Other features of note in this micrograph are arteries (A) and veins (V) which are found coursing in the connective tissue with the larger ducts. Also evident in this micrograph is an area containing an accumulation of lymphocytes and plasma cells (LP).