Myoepithelial cell differentiation in rat mammary glands
Radnor, C.J.
Journal of Anatomy 111(Pt 3): 381-398
1972
ISSN/ISBN: 0021-8782 PMID: 4560931 Document Number: 45966
Light and electron microscopy was used to study growth and differentiation of mammary tissue of Sprague-Dawley rats aged 2-70 days. Although mitoses were observed against the basement membrane, near the lumen and in the parenchyma it seemed unlikely that differentiated myoepithelial cells would themselves divide. It was thought that undifferentiated 'pale cells' found in the duct parenchyma gave rise to myoepithelial cells by movement towards the basement membrane and to colummar epithelial cells by movement luminally. During differentiation into myoepithelial cells, the pale cells became flattened and their nuclei became elongated and more irregular in outline with more aggregated chromatin. Endoplasmic reticulum was dilated and ribosomal clusters were formed. Formation of hemidesmosomes in the basal surface followed, and development of myofilaments in association with attachment areas along the plasma membrane and of dense bodies in the cytoplasm occurred.