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 irregular ly shaped cells with a central body containing the nucleus and numerou s long cytoplasmic processes embracing the basal surface of the secret ory cells. The main identifying feature of myoepithelial cells was the numerous myofilaments that occupied much of the cytoplasm. Quantitati ve studies with the electron microscope revealed significant differenc es between male and female glands, being either volume fraction and nu merical 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 responsib le for the sex difference. The functional significance of this sex dif ference is discussed in relation to the different secretory activity o f the Harderian gland in the two sexes.