Abolition of SIRT1 enzymatic activity results in blunted ductal morphogenesis in the mammary gland.

<p>Right panel, representative photographs of whole mounts of the 4^th abdominal mammary gland in <i>Sirt1</i>^+/+, <i>Sirt1</i>^Y/+ and <i>Sirt1</i>^Y/Y mice at eleven weeks of age (scale bar, 5mm). Left panel, a higher magnification view of the ductal network in representative mammary gland whole mounts of the 4^th abdominal mammary gland in <i>Sirt1</i>^+/+, <i>Sirt1</i>^Y/+ and <i>Sirt1</i>^Y/Y mice at eleven weeks of age. 400X magnification (scale bar, 0.7 mm).