Scanning Electron Microscopic Observations of the Myoepithelial Cells of Normal and Contracting Status in the Rat Harderian Gland

The stromal surface of the myoepithelial cells of normal and contracting status in the rat Harderian gland has been studied by SEM after removal of the connective tissue elements by HC1 and collagenase. The flattened myoepithelial cell has an elongated central perikaryon from which radiate out 6 to 9 broad primary processes bifurcating two or three times to produce a total complement of 15 to 28 terminal ones per cell, each 1 to 2.5.μ wide. The terminal processes are contiguous with those of adjacent myoepithelial cells to grasp the alveolus in the fashion of a network. They mostly meet end to side or end to end and occasionally overlap each other. After injection of acetylcholine, the myoepithelial cells had prominent irregular folds squeezing the alveoli probably due to contraction of them.