Morphological study of the parotid duct in human fetuses with special emphasis on the relationship between the buccinator muscle and the parotid duct

Kaori Amano, Hiroshi Moriyama, Kazuyuki Shimada, George Matsumura
2009 Journal of Medical Investigation  
were prepared. They consisted of the following ages : three five-month-old fetuses, seven sixmonth-old fetuses, six seven-month-old fetuses, eight nine-month-old fetuses, and six ten-month-old fetuses. Their ages were determined by measuring their body lengths. These specimens were perfused with 10% formaldehyde fixative. After removing the facial skin, each parotid duct from the entrance of the buccinator muscle to the opening of the oral cavity along with its surrounding buccinator muscle was
more » ... ccinator muscle was removed en bloc ( Fig. 1) . Twenty specimens were cut open from the entrance of the buccinator muscle toward the opening of the oral cavity under a dissection light microscope for morphological examination prior to scanning electron microscope (SEM) observation. After conductive staining with tannin-osmium (1%) solution, we dehydrated them with alcohol and used the tbutyl alcohol freeze drying method for preparing MINI REVIEW Abstract : Parotid glands secrete about 25% % of all saliva produced in the salivary glands. In the presence of a stimulus, the amount of saliva secreted from the parotid gland increases to 50% % (1). In human adults, the parotid duct, approximately 6-8 cm long, traverses the masseter muscle and penetrates through the buccinator muscle into the oral cavity. Although various studies have been conducted on the parotid gland, there are only few suggesting the functional roles of the parotid duct, especially of the area penetrating the buccinator muscle. In the present study, we observed parotid ducts of human fetuses to morphologically analyze the function of the buccinator muscles in the flux of parotid saliva. Thirty fetal specimens ranging from five to ten months of age were dissected for anatomical and histological examinations. The area of the parotid duct penetrating the buccinator muscle was fully formed in six-month-old fetuses. Furthermore, this study confirms the existence of thin buccinator muscle fibers underneath the epithelium of the parotid duct's distal portion. Results suggest that the buccinator muscle may play a major role in preventing the reflux of salivary secretions by assisting the contraction of the parotid duct. J. Med. Invest. 56 Suppl. : 255-257, December, 2009
doi:10.2152/jmi.56.255 pmid:20224193 fatcat:byxafgftcbcgteis3r467hiysi