A morphometric and fine structural study of the myoepithelial cells in the hamster harderian gland.

Myoepithelial cells were structurally and morphometrically studied in the hamster Harderian gland. Myoepithelial cells appeared as irregularly shaped cells with a central body containing the nucleus and numerous long cytoplasmic processes embracing the basal surface of the secretory cells. The main identifying feature of myoepithelial cells was the numerous myofilaments that occupied much of the cytoplasm. Quantitative studies with the electron microscope revealed significant differences between male and female glands, being either volume fraction and numerical density of myoepithelial cells higher in female glands than in male glands. No evidence of cellular size variation between sexes was found. Cell number differences, rather than cell size, were responsible for the sex difference. The functional significance of this sex difference is discussed in relation to the different secretory activity of the Harderian gland in the two sexes.