Figure 5.

Systemic hormonal stimulation by suckling or glucocorticoids alone preserve lobular-alveolar structure without blocking PCD. Histological analyses of mammary tissue from WAP-TAg transgenic mice in the absence (A) and presence (B and C) of suckling or after exogenous glucocorticoids (D). Hematoxylin and eosin staining (A and B). In situ detection of PCD (C and D). Arrows indicate cells undergoing PCD. TAg, WAP-TAg transgenic mouse; inv 3d, 3 days involution; suc 3d, 3 days suckling; +H, hydrocortisone injected mouse. (E) Northern blot analyses of β-casein expression in 3 days suckled TAg mice. Loading control, ethidium bromide staining of 18S and 28S RNA; P, day 18 pregnancy; suckling 3d, samples from individual TAg mice suckled for 3 days; I 3d, 3 days involution.