OBJECTIVETo investigate the changes in the number and distribution of myoepithelial cells during atrophy of the rat parotid gland.

METHODSAtrophy of the right parotid was induced by ligating the right stensen duct of rats, histological changes of parotid glands were examined by hematoxylin-eosin (HE) staining during each step of glandular atrophy at the time of 0 (control), 1, 3, 5, 7, 14, 21, 30, 60, 100, and 150 days after ligation. Immunohistochemical labelling was performed to study the changes in number and distribution of myoepithelial cells during atrophy of the rat parotid gland.

RESULTSHistological analysis showed disappearance of the acini at 5 d and gradual decrease and fibrosis of the glandular lobules accompanied by the occurrence of duct-like structures. Quantitative analysis of myoepithelial cells showed significant increase in number up to day 5 after ligation, then followed by gradual increases at a low level, at last it was followed by a rapid decrease after the total number reached the peak in 100 days. In addition, the acini and intercalated ducts were covered by myoepithelial cells ranged from the shape of spindle to stellate during the early phase of atrophy, while spindle-shaped myoepithelial cells were located at the periphery of duct-like structures in the later phase of atrophy.

CONCLUSIONMyoepithelial cells proliferated rapidly up to day 5 after ligation, then followed by gradual increase at a low level, at last it was followed by a rapid decrease after the total number reached the peak in 100 days.