Abstract
Terminal ductules of the resting mammary glands of young adult female rats were studied by an electron microscope to determine the limits of normal ultrastructural variability.
Fine pieces of the abdominal mammary-fatty tissues of Sprague-Dawley fem a le rats, aged 50-150 days, were packed into a small wire-meshed cago, and then fixed satisfactorily in Karnovsky's fixatives and postfixed in osmium tetroxide buffered with veronal-acetate. Sufficient dehydration in graded alcohols and propylene oxide was followed by embedding in Epon. After the careful trimmings, sections were cut on an ultrathin microtome and stained with uranyl acetate and lead citrate.
