Figure 11

Localization of latent TGFβ binding protein (Ltbp)1 and elastin in the pubertal and pregnant mammary gland. Immunofluorescent detection of Ltbp1 (A, B and D), elastin (C , E) and smooth-muscle actin (SMA) (A-E) in frozen sections of mammary glands isolated from 6-week-old pubertal (A-C) and 14.5-day pregnant mice (D, E). Anti-SMA detected by Alexa-488 secondary antibodies (green) localized basal myoepithelial cells of mature ducts but not cap cells of the terminal end bud (TEB) and robustly stained basal cells of alveoli. Anti-Ltbp1 detected by Cy3-coupled secondary antibodies (red in center panels) in virgin (A, B) and pregnant glands (D) detected Ltbp1 deposited in close apposition to the SMA-positive basal cell layer (yellow in right merged panel). In contrast the cap cell layer that surrounds the TEB was negative with both anti-SMA and anti-Ltbp1 antibodies. Anti-tropoelastin detected by Cy3 coupled secondary antibodies (red in center and right panels) in virgin (C) and pregnant (E) glands detects elastic fibers surrounding the basal layer. Both Ltbp1 and elastic fibers are excluded from alveolar clusters. Frozen sections were viewed under a Carl Zeiss Confocal LSM510 microscope at 20× magnification and images were acquired using Zen Software version 2010. Scale bars represent distance in microns. DAPI, 4',6-diamidino-2-phenylindole.